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 A247831 #22 Feb 13 2019 20:12:13
%S A247831 12327121,129816911251,259621495381,346157884801,605767053061,
%T A247831 6317168754781,6922923480721,12634325182441,18518799663001,
%U A247831 21634109682121,24273469559431,57114029344321,65681131896901,102718706568661,135083316211741,135818875521811,153342494379361
%N A247831 Pseudoprimes to base 2 divisible by 3511^2, including the even pseudoprimes.
%C A247831 Numbers k such that 2^k == 2 (mod k) and k is divisible by 3511^2.
%C A247831 Unless there are other Wieferich primes (A001220) besides 1093 and 3511, the intersection and the union of this sequence with A247830 are given by A219346 and A158358, respectively, and the even terms are given by A295740. - _Max Alekseyev_, Nov 26 2017 [The indices of the even terms in this sequence are 430, 525, 543, 701, 811, 826, 937, 1235, 1277, 1388, ... - _Jianing Song_, Feb 08 2019]
%H A247831 Jianing Song, <a href="/A247831/b247831.txt">Table of n, a(n) for n = 1..1470</a>
%H A247831 R. G. E. Pinch, <a href="http://dx.doi.org/10.1007/10722028_30">The pseudoprimes up to 10^13</a>, Lecture Notes in Computer Science, 1838 (2000), 459-473.
%H A247831 C. Pomerance, J. L. Selfridge, and S. S. Wagstaff, Jr., <a href="http://dx.doi.org/10.1090/S0025-5718-1980-0572872-7">The pseudoprimes to 25*10^9</a>, Mathematics of Computation 35 (1980), pp. 1003-1026.
%o A247831 (PARI) vi=readvec("b158358.txt")
%o A247831 for(n=1, #vi, if(Mod(vi[n], 3511^2)==0, print1(vi[n], ", ")))
%o A247831 (PARI) list(N)=select(k->Mod(2, k)^k==2, 3511^2*vector(N\3511^2\2, i, i)) \\ _Jianing Song_, Feb 07 2019
%Y A247831 Subsequence of each of (A001567 U A006935), A015919, A158358 composed of the terms divisible by 3511^2.
%Y A247831 Cf. A001220, A013929, A219346, A247830, A295740.
%K A247831 nonn
%O A247831 1,1
%A A247831 _Felix Fröhlich_, Sep 24 2014
%E A247831 Name changed by _Jianing Song_, Feb 07 2019 to include the even pseudoprimes to base 2 (A006935) at the suggestion of _Max Alekseyev_.