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 A298944 #14 Feb 27 2018 12:31:10
%S A298944 8,32,0,13,12,32,156,184,0,176,288,319,464,320,341,496,40,64,212,0,
%T A298944 301,308,9,1040,952,472,1088,1544,800,391,508,2048,1191,1312,922,2608,
%U A298944 284,2359,1920,688,1800,3488,2668,2524,0,2291,428,144,3109,2612,1472,2888
%N A298944 a(n) = 2^(c-1) mod c^2, where c is the n-th composite number.
%C A298944 a(n) = 0 iff c is a term of A000079 > 4.
%C A298944 Composites c where a(n) = 1 could be called "Wieferich pseudoprimes". Do any such composites exist?
%C A298944 A necessary condition for c to be a "Wieferich pseudoprime" would be that it is a term of both A001567 and A270833 (see comments in A240719).
%H A298944 Robert Israel, <a href="/A298944/b298944.txt">Table of n, a(n) for n = 1..10000</a>
%p A298944 map(c -> 2&^(c-1) mod c^2, remove(isprime, [$4..1000])); # _Robert Israel_, Feb 27 2018
%t A298944 composite[n_Integer] := FixedPoint[n + PrimePi@ # + 1 &, n + PrimePi@ n + 1]; Array[With[{c = composite@ #}, Mod[2^(c - 1), c^2]] &, 52] (* _Michael De Vlieger_, Jan 31 2018, composite function by _Robert G. Wilson v_ at A066277 *)
%o A298944 (PARI) forcomposite(c=1, 200, print1(lift(Mod(2, c^2)^(c-1)), ", "))
%Y A298944 Cf. A000079, A001220, A001567, A240719, A270833, A298945, A298946.
%K A298944 nonn
%O A298944 1,1
%A A298944 _Felix Fröhlich_, Jan 30 2018