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 A228455 #14 Aug 06 2017 18:43:42 %S A228455 280743771536011785,666787209284980785,1386744766793550165, %T A228455 6558237049521329745,11646802313400102465 %N A228455 Pseudoprimes n to base 2 such that n-2, n+2, n-4 and n+4 are primes. %C A228455 All numbers in this sequence end in 5 because n-4 , n-2 is a twin prime pair and so also is n+2 and n+4. %C A228455 For all n, a(n) - 4 is in A230668(n). Somewhat surprisingly, all terms of A230668 known so far are of that form. - _M. F. Hasler_, Dec 08 2016 %e A228455 280743771536011785 is a pseudoprime (base 2) and 280743771536011781, 280743771536011783, 280743771536011787 and 280743771536011789 are primes. %Y A228455 Cf. A001567, A057942, A230488, A230489. %K A228455 nonn,more,hard %O A228455 1,1 %A A228455 _Shyam Sunder Gupta_, Oct 27 2013