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 A237266 #7 Feb 25 2014 21:23:24
%S A237266 1,1,1,2,1,3,1,1,2,2,3,1,1,1,1,1,1,3,1,1,1,3,1,2,1,1,1,1,1,1,1,3,1,1,
%T A237266 2,1,1,1,1,5,1,1,1,1,2,1,1,1,1,3,1,1,5,2,1,3,1,1,1,1,1,3,1,1,1,1,1,4,
%U A237266 1,2,2,1,1,1,2,2,1,2,3,2,2,1,5,1,1,3,1
%N A237266 The n-th base 2 pseudoprime is also a pseudoprime to base 2 through base prime(a(n)).
%C A237266 Pseudoprime A001567(n) is a pseudoprime to base 2 through base prime(a(n)), where a(n) is this sequence.
%H A237266 Lei Zhou, <a href="/A237266/b237266.txt">Table of n, a(n) for n = 1..10000</a>
%e A237266 n=1, A001567[1]=341. 341 is base 2 pseudoprime but not base 3 pesudoprime. Since Prime(1)=2, a(1)=1;
%e A237266 ...
%e A237266 n=6, A001567[1]=1729. 1729 is base 2, 3, 5 pseudoprimes but not base 7 pesudoprime. Since Prime(3)=5, a(6)=5.
%t A237266 p = 1; fi = {}; While[Length[fi] < 87, p = p + 2; If[! PrimeQ[p], ct = 0; q = 2; While[c = q^(p - 1); Mod[c, p] == 1, q = NextPrime[q]]; If[q > 2, q = PrimePi[NextPrime[q, -1]]; AppendTo[fi, q]]]]; Print[fi]
%Y A237266 Cf. A001567, A083876, A002997.
%K A237266 nonn
%O A237266 1,4
%A A237266 _Lei Zhou_, Feb 05 2014