A091982 - OEIS

%I #11 May 07 2017 10:05:35

%S 1,4181,6721,13201,34561,51841,64681,90061,96049,97921,163081,186961,

%T 197209,268801,283361,302101,330929,399001,489601,520801,636641,

%U 655201,920577,999941,1034881,1072513,1081649,1084201,1106561,1317121,1346269,1392169,1533601

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

%H Giovanni Resta, <a href="/A091982/b091982.txt">Table of n, a(n) for n = 1..2500</a>

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

%Y For primes see A047272.

%K nonn,easy

%O 1,2

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

%E a(16)-a(33) from _Giovanni Resta_, May 06 2017