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Sum of squares of Fibonacci numbers 1,2,3,5,... that divide n.
1

%I #32 Apr 03 2020 03:38:24

%S 1,5,10,5,26,14,1,69,10,30,1,14,170,5,35,69,1,14,1,30,451,5,1,78,26,

%T 174,10,5,1,39,1,69,10,1161,26,14,1,5,179,94,1,455,1,5,35,5,1,78,1,30,

%U 10,174,1,14,3051,69,10,5,1,39

%N Sum of squares of Fibonacci numbers 1,2,3,5,... that divide n.

%H Vaclav Kotesovec, <a href="/A005093/b005093.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..100 from Indranil Ghosh)

%F G.f.: Sum_{k>=2} Fibonacci(k)^2*x^Fibonacci(k)/(1 - x^Fibonacci(k)). - _Ilya Gutkovskiy_, Mar 21 2017

%t nmax = 100; With[{fibs = Fibonacci[Range[2, Floor[Log[nmax*Sqrt[5]] / Log[GoldenRatio]] + 1]]}, Table[Total[Select[fibs, Divisible[n, #1] & ]^2], {n, 1, nmax}]] (* _Harvey P. Dale_, Apr 25 2011, fixed by _Vaclav Kotesovec_, Apr 29 2019 *)

%o (Python)

%o from sympy import divisors, fibonacci

%o l = [fibonacci(n) for n in range(1, 21)]

%o def a(n):

%o return sum(i**2 for i in divisors(n) if i in l)

%o print([a(n) for n in range(1, 101)]) # _Indranil Ghosh_, Mar 22 2017

%Y Cf. A000045, A005092.

%K nonn

%O 1,2

%A _N. J. A. Sloane_

%E Offset changed from 0 to 1 by _Ilya Gutkovskiy_, Mar 21 2017

%E b-file corrected by _Vaclav Kotesovec_, Apr 29 2019