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 A230488 #7 Oct 22 2013 12:54:48 %S A230488 645,33153,129921,157641,451905,656601,1608465,3020361,3370641, %T A230488 6212361,19092921,34487601,38790753,681942801,940492785,1109260545, %U A230488 1574300001,2693081973,3037396461,4160578521,6424683105,7384487181,13671360561,14966031345,15731001105 %N A230488 Pseudoprimes n to base 2 such that n-2 and n-4 are primes. %H A230488 Shyam Sunder Gupta, <a href="/A230488/b230488.txt">Table of n, a(n) for n = 1..7173</a> %e A230488 645 is a pseudoprime (base 2) and 643 and 641 are primes. %Y A230488 Cf. A001567, A057942. %K A230488 nonn %O A230488 1,1 %A A230488 _Shyam Sunder Gupta_, Oct 20 2013