Wenpeng Zhang. Research Center for Basic Science, Xi'an Jiaotong University. Xi'an Shaanxi, People's Republic of China

Transcription

1 On the Smarache Lucas base related counting function l Wenpeng Zhang Research Center for Basic Science, Xi'an Jiaotong University Xi'an Shaanxi, People's Republic of China. INTRODUCTION AND RESULTS As usual, the Lucas sequence {Ln} the Fibonacci sequence {Fn} (. 0,,2,...,) are defined by the second-order linear recurrence sequences for n ~ 0, Lo = 2, L =, Fo = 0 FI =. These sequences playa very important role in the studies of the theory application of mathematics. Therefore, the various properties of Ln Fn were investigated by many authors. For example, R. L. Duncan [] L. Kuipers [2J proved that (logfn) is uniformly distributed mod. H.London R.Finkelstein [3] studied the Fibonacci Lucas numbers which are perfect powers. The author [4] obtained some identities involving the Fibonacci numbers. In this paper, we introduce a new counting function a(m) related to the Lucas numbers, then use elementary methods to give an exact calculating formula for its mean value. First we consider the Smarache's generalized base, Professor F.Smarach defined over the set of natural numbers the following infinite generalized base: = go < gl <... < gk <... He proved that every positive integer N may be uniquely written in the Smarache Generalized Ba..c;e a.s: n N=L(f.i9j, ;=0 with 0 < 0i < [9i+ - ] - - gi' This work is supported by the ~.S.F. anj P.N.S.F. of P.R.China. 9

2 (integer part) for i = 0,,,n. of course an 2:, in the following way: if so on untill one obtains a rest rj = o. This base is important for partitions. If we take the gi as the Lucas sequence, then we can get a particular base, for convenience, we refer to it as a Smarache Lucas base. Then any positive integer m may be uniquely written in the Smarache Lucas base as: n m = L aili, with all ai = 0 or, i=l () That is, any positive integer may be written as a sum of Lucas numbers. Now for n an integer m = L aili, we define the counting function a( m) = a + a an. i=l The main purpose of this paper is to study the distribution properties of a( m), present a calculating formula for the mean value Ar(N) = L ar(n), r =, 2. (2) n<n That is, we prove the following two main conclusions: Theorem. For any positive integer k, 'we have the calculating formulae A(Lk) = L a(n)=kfk- n<lk Theorem 2. For any positive integer N, let N = Lkl + Lk Lk. with kl > k2 >... > ks under the Smarache Lucas base. Then we have 92

3 Further, s Al(N) = L [kifk;-l + (i -l)lkj. ;= For any positive integer r ~ 3, using our methods we can also give an exact calculating formula for AALk). But in these cases, the computations are more complex. 2. PROOF OF THE THEOREMS In this section, we complete the proof of the Theorems. First we prove Theorem by induction. For k =, 2, we have A(Ld = Al(l) = 0, A (L 2 ) = Al(3) = 2 Fo = 0, 2Fl = 2. So that the identity A(Lk ) = L a(n) = kfk-l (3) n<lic holds for k = 2. Assume (3) is true for all k ~'m -. Then by the inductive assumption we have Al(Lm) = L a(n) + L a(n) n<lm_ Lm_$n<Lm = Al(Lm - ) + L a(n + L m - l ) O$n<L m _ 2 =A (Lm - )+ L (a(n) + ) O$n<L m _ 2 =Al(Lm-d+Lm-2+ L a(n) n<lm_ 2 = (m -)F m (m - 2)Fm L m - 2 = m(fm Fm - 3 ) - Fm - 2-2Fm L m - 2 = mfm - l - Fm - - Fm L m - 2 = mf m -, where we have used the identity F m - l + F m - 3 = L m - 2 That is, (3) is true for k = m. This proves the first part of Theorem. 93

4 Now we prove the second part of Theorem. For k =, 2, note that = F = Fo + F- or F- =, we have A2(LI) =.4. 2 () = 0, A 2(L2) = A 2(3) = 2 5 [ (k - l)(k - 2)Lk-2 + 5(k -)Fk- { 0, 2 + 7(k - )Fk Fk- ] = 2, if k = ; if k = 2. So that the identity A 2(Lk) = 5 [(k - l)(k - 2)Lk (k - )Fk-2 + 7(k -)Fk-3 + 3Fk-d (4)' holds for k =, 2. Assume (4) is true for all k ~ m -. Then by the inductive assumption, the first part of Theorem note that L m - + 2L m - 2 = 5F m -; F m - + 2F m - 2 = L m -, we have = A2(Lm-d + A2(Lm - 2 ) + 2A(Lm - 2) + L m - 2 = 5 [em - 2)(m - 3)L rn (m - 2)Fm (m - 2)Fm Frn - 2 ] + 5 [em - 3)(m - 4)Lm-4 + 5(m - 3)Fm (m - 3)Fm- s + 3Fm- 3 ] + 2(m - 2)Fm L m - 2 = ~ [em -l)(m - 2)L rn (m - )Fm (m -)Fm Frn - 2 ] [em - l)(m - 2)L m (m - )Fm (m - l)fm - s + 3Fm - 3 ] - ~ [2(rn - )L rn (4m -0lL m F m Fm Fm F m - s] +2(m -2)Fm - 3 +Lm - 2 = ~ [em -l)(m - 2)Lm (m - )Fm (m - )Fm Fm - ] 94

5 - -:- [2(m - 2)(Lm Lm - 4 ) - 2L m (F m F m - 4 ) oj. + 7(Fm Fm - 5 )] + 2(m - 2)F m L m - 2 = 5" [(m - l)(m - 2)Lm (m - I)Fm (m - I)F m F~-] - 5" [0( )Fm - 3-2Lm L m L m - 4 ] + 2(m - 2)Fm - 3+ Lm - 2 = 5" ((m -l)(m - 2)Lm (m - I)F m (m - I)F m Fm-d. That is, (4) is true for k = m. This completes the proof of Theorem. Proof of Theorem 2. Note that N = Lkl + Lk Lk., applying Theorem we have Al(N) = L a(n) + L a(n) n<lkl Lkl $;n<n = A(Lk ) + L a(n) Lkl $.n<n L (a(n) + ) (a 2 (n) + 2a(n) + ) O$.n<N-Lk l = A 2(LkJ + N - Lkl + A 2(N - LkJ + 2A(N - LkJ. This proves the first part of Theorem 2. The final formula in Theorem 2 can be proved using induction on.s the recursion formulae. This completes the proof of Theorem 2. 95

6 REFERENCES. Duncan, RL., Application of Uniform Distribution to the Fibonacci Nu.mbers, The Fibonacci Quarterly 5 (967), Kuipers,., Remark on a paper by R. L. Duncan concerning the uniform distrubu.tion mod of the sequence of the Logarithms of the Fibonacci numbers, The Fibonacci Quarterly 7 (969), London, H. Finkelstein, R., On Fibonacci Lucas numbers which are perfect powers, The Fibonacci Quarterly 7 (969), l. 4. Wenpeng Zhang, Some identities involving the Fibonacci numbers, The Fibonacci Quarterly 35 (997), Robbins, N., Applications of Fibonacci Numbers, Kluwer Academic publishers, 986, pp Dumitrescu, C., Seleacu, V., Some notions questions in number theory, Xiquan Pub!. Hse., Glendale, 994, Section # Grebenikova, Irina, Some Bases of Numerations (Abstracts of Papers Presented at the American Mathematical Society), Vol. 7, No.3, Issue 05, 996, p "Smarache Bases" at 96