OFFSET
1,2
COMMENTS
Numbers k such that A000045(k+1) == 1 (mod k). - Robert Israel, Oct 13 2015
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
FORMULA
a(n) = A101907(n) + 1. - Altug Alkan, Dec 29 2015
EXAMPLE
Sum of first 6 Fibonacci numbers is 0+1+1+2+3+5 = 12. Because 6 divides 12, 6 is in the sequence.
MAPLE
fmod:= proc(a, b) local A, n, f1, f2, f;
uses LinearAlgebra[Modular];
A:= Mod(b, <<1, 1>|<1, 0>>, integer[8]);
MatrixPower(b, M, a)[1, 2];
end proc:
1, op(select(t -> fmod(t+1, t) = 1, [$2..10^4])); # Robert Israel, Oct 13 2015
MATHEMATICA
okQ[n_] := n == 1 || Mod[Fibonacci[n+1], n] == 1;
Select[Range[1000], okQ] (* Jean-François Alcover, Feb 04 2023 *)
PROG
(Python)
sum, prpr, prev = 0, 0, 1
for i in range(1, 1000):
sum += prpr
if sum % i == 0: print i,
prpr, prev = prev, prpr+prev
(PARI) lista(nn) = {sf = 0; for (n=0, nn, sf += fibonacci(n); if (sf % (n+1) == 0, print1(n+1, ", ")); ); } \\ Michel Marcus, Jun 05 2013
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Alex Ratushnyak, May 03 2013
STATUS
approved