This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A174620 #16 Jul 01 2024 12:44:21
%S A174620 1,2,1,1,3,5,4,11,8,27,2,36,1,42,24,13,11,19,45,5,8,50,71,2,86,78,15,
%T A174620 74,16,112,4,68,14,106,66,32,79,26,25,18,76,6,78,150,163,63,69,98,189,
%U A174620 17,184,40,1,125,249,187,229,69,169,81,264,172,18,209,114,277,1,128,46,21
%N A174620 a(n) = 2^A141468(n) mod prime(n), where A141468(n) is the n-th nonnegative nonprime.
%H A174620 Paolo Xausa, <a href="/A174620/b174620.txt">Table of n, a(n) for n = 1..10000</a>
%e A174620 a(14) = 12 because (2^A141468(14) mod prime(14)) = (2097152 mod 43) = 12.
%t A174620 MapIndexed[PowerMod[2, #, Prime[First[#2]]] &, Join[{0, 1}, Select[Range[100], CompositeQ]]] (* _Paolo Xausa_, Jul 01 2024 *)
%o A174620 (PARI) c=-1; forprime(p=1,999,while(isprime(c++),);print1(lift( Mod(2,p)^c )", ")) \\ _M. F. Hasler_, Nov 29 2010
%Y A174620 Main diagonal of A177416.
%Y A174620 Cf. A000040, A000079, A141468.
%K A174620 nonn
%O A174620 1,2
%A A174620 _Juri-Stepan Gerasimov_, Nov 29 2010