OFFSET
1,2
COMMENTS
a(n) is a union of {1}, A069106(n) and A045468(n). Composite a(n) are listed in A069106(n) = {442, 1891, 2737, 4181, 6601, 6721, 8149, ...}. Prime a(n) are listed in A045468(n) = {11, 19, 29, 31, 41, 59, 61, 71, 79, 89, 101, 109, 131, 139, 149, 151, 179, 181, 191, 199, ...} Primes congruent to {1, 4} mod 5. - Alexander Adamchuk, Nov 02 2006
LINKS
Reinhard Zumkeller, Table of n, a(n) for n = 1..1000
EXAMPLE
Fibonacci(10) = 55, is divisible by 11.
MATHEMATICA
Select[Range[1000], IntegerQ[Fibonacci[ # - 1]/# ] &]
PROG
(Haskell)
import Data.List (elemIndices)
a123976 n = a123976_list !! (n-1)
a123976_list = map (+ 1) $ elemIndices 0 $ zipWith mod a000045_list [1..]
-- Reinhard Zumkeller, Oct 13 2011
(PARI) is(n)=((Mod([1, 1; 1, 0], n))^n)[2, 2]==0 \\ Charles R Greathouse IV, Feb 03 2014
CROSSREFS
KEYWORD
nonn
AUTHOR
Tanya Khovanova, Oct 30 2006
STATUS
approved