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 A230489 #6 Oct 22 2013 12:55:22 %S A230489 87249,831405,1489665,2113665,31880577,81612105,84028407,86559045, %T A230489 274014885,1778357505,1853263365,2276082537,9090685605,12300409857, %U A230489 43620860865,69654751377,248342283645,634038307449,848282877345,1123296404385,1344952805505,3307428792777 %N A230489 Pseudoprimes n to base 2 such that n+2 and n+4 are primes. %H A230489 Shyam Sunder Gupta, <a href="/A230489/b230489.txt">Table of n, a(n) for n = 1..1076</a> %e A230489 87249 is a pseudoprime (base 2) and 87251 and 87253 are primes. %Y A230489 Cf. A001567, A057942. %K A230489 nonn %O A230489 1,1 %A A230489 _Shyam Sunder Gupta_, Oct 20 2013