A091982 Nonprimes n such that Mod(n,4) == 1 and denominator(Fibonacci((n-1)/4)/n) = 1.

1, 4181, 6721, 13201, 34561, 51841, 64681, 90061, 96049, 97921, 163081, 186961, 197209, 268801, 283361, 302101, 330929, 399001, 489601, 520801, 636641, 655201, 920577, 999941, 1034881, 1072513, 1081649, 1084201, 1106561, 1317121, 1346269, 1392169, 1533601

Offset: 1

Author

Mohammed Bouayoun (bouyao(AT)wanadoo.fr), Mar 17 2004

Keywords

• nonn
• easy

Links

• Giovanni Resta, Table of n, a(n) for n = 1..2500

Crossrefs

For primes see A047272.

Programs

Mathematica

Select[Range[1, 10^6, 4], And[! PrimeQ@ #, Denominator[Fibonacci[(# - 1)/4]/#] == 1] &] (* Michael De Vlieger, May 07 2017 *)

Extensions

a(16)-a(33) from Giovanni Resta, May 06 2017