login
A130155
a(1)=1. a(n) = number of earlier terms of the sequence that divide the n-th Fibonacci number.
2
1, 1, 2, 2, 2, 5, 2, 2, 7, 3, 2, 9, 2, 2, 11, 4, 2, 12, 2, 5, 12, 2, 2, 20, 4, 2, 15, 3, 2, 22, 2, 5, 17, 2, 5, 26, 2, 2, 20, 11, 2, 24, 2, 4, 27, 2, 2, 34, 2, 8, 25, 4, 2, 33, 6, 5, 26, 2, 2, 52, 2, 2, 34, 5, 8, 36, 2, 4, 31, 10, 2, 52, 2, 2, 42, 4, 2, 43, 2, 15, 39, 2, 2, 59, 8, 2, 39, 6, 2, 65, 2
OFFSET
1,3
EXAMPLE
The 10th Fibonacci number is 55. Among terms (a(1), a(2), ..., a(9)) there are 3 terms (a(1)=1, a(2)=1, a(6)=5) that divide 55, so a(10) = 3.
MAPLE
A130155 := proc(nmax) local a, nfib, anew, i; a := [1] ; while nops(a) < nmax do n := nops(a)+1 ; nfib := combinat[fibonacci](n) ; anew :=0 ; for i from 1 to nops(a) do if nfib mod op(i, a) = 0 then anew := anew+1 ; fi ; od ; a := [op(a), anew] ; od ; RETURN(a) ; end: A130155(100) ; # R. J. Mathar, Jun 07 2007
MATHEMATICA
seq[nmax_] := Module[{a, nfib, anew, i}, a = {1}; While[Length[a] < nmax , n = Length[a]+1; nfib = Fibonacci[n]; anew = 0; For[i = 1, i <= Length[a], i++, If[Mod[ nfib, a[[i]]] == 0 , anew = anew+1]]; AppendTo[a, anew]]; Return[a]]; seq[100] (* Jean-François Alcover, Nov 18 2013, translated from Maple *)
nn = 1000; t = {1}; Do[cnt = 0; fibn = Fibonacci[n]; Do[If[Mod[fibn, t[[k]]] == 0, cnt++], {k, n - 1}]; AppendTo[t, cnt], {n, 2, nn}]; t (* T. D. Noe, Nov 18 2013 *)
CROSSREFS
Sequence in context: A112659 A342550 A115281 * A350403 A113516 A226525
KEYWORD
nonn
AUTHOR
Leroy Quet, May 13 2007
EXTENSIONS
More terms from R. J. Mathar, Jun 07 2007
STATUS
approved