A213337 - OEIS

%I #22 Jul 24 2021 05:39:23

%S 143,399,527,779,1501,1679,2407,2627,2703,2737,3239,3289,3599,3827,

%T 4031,4033,4879,4991,5183,5291,5719,5921,6479,6601,6721,7739,8321,

%U 8687,8903,9361,9503,10153,10439,11537,11663

%N Odd composite numbers k that divide the imaginary part of (1+2i)^A201629(k).

%C The odd terms of A212502.

%H Amiram Eldar, <a href="/A213337/b213337.txt">Table of n, a(n) for n = 1..10000</a>

%t t[n_]:=Which[Mod[n,4]==3,n+1,Mod[n,4]==1,n-1,True,n]; Select[1+ Range[1000], Mod[#,2]==1&&! PrimeQ[#] && Im[PowerMod[1 + 2I, t[#], #]] == 0 &]

%Y Cf. A201629, A212502.

%K nonn

%O 1,1

%A _José María Grau Ribas_, Jun 09 2012