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 A108568 #7 Jun 03 2013 09:03:43 %S A108568 2,3,5,9,13,17,21,25,33,39,45,53,57,61,69,79,85,91,99,103,109,117,125, %T A108568 137,147,151,155,159,163,179,195,203,209,219,229,235,245,253,261,271, %U A108568 277,287,297,301,305,317,339,353,357,361,369,375,385,399,409,419,425 %N A108568 a(n) = prime(n) + prime(n+1) - 2n - 1. %o A108568 (PARI) a(n) = prime(n) + prime(n+1) - 2*n - 1 \\ _Michel Marcus_, Jun 03 2013 %Y A108568 Cf. A108562. %K A108568 easy,nonn %O A108568 1,1 %A A108568 _Giovanni Teofilatto_, Jul 05 2005 %E A108568 Extended by _Ray Chandler_, Jul 10 2005