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 A123976 Numbers n such that Fibonacci(n-1) is divisible by n. 10
 1, 11, 19, 29, 31, 41, 59, 61, 71, 79, 89, 101, 109, 131, 139, 149, 151, 179, 181, 191, 199, 211, 229, 239, 241, 251, 269, 271, 281, 311, 331, 349, 359, 379, 389, 401, 409, 419, 421, 431, 439, 442, 449, 461, 479, 491, 499, 509, 521, 541, 569, 571, 599, 601 (list; graph; refs; listen; history; text; internal format)
 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 Cf. A069106, A045468, A069104, A069107, A003631, A000045, A023172, A159051. Sequence in context: A125771 A158290 A057538 * A045468 A196095 A268271 Adjacent sequences:  A123973 A123974 A123975 * A123977 A123978 A123979 KEYWORD nonn AUTHOR Tanya Khovanova, Oct 30 2006 STATUS approved

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Last modified October 19 04:40 EDT 2019. Contains 328211 sequences. (Running on oeis4.)