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 A068511 #3 Mar 30 2012 16:49:19 %S A068511 0,0,2,-2,14,-2,146,82,-46,-302,1286,262,25934,21838,13646,-2738, %T A068511 444974,379438,9437546,9175402,8651114,7602538,218898566,214704262, %U A068511 206315654,189538438,155984006,88875142,6201257774,5932822318,199486748306,198413006482,196265522834,191970555538 %N A068511 (Product of primes <= n) - 2^(n-1). %Y A068511 Cf. A059794, A068511. %K A068511 sign,easy %O A068511 1,3 %A A068511 _N. J. A. Sloane_, Mar 21 2002 %E A068511 More terms from Larry Reeves (larryr(AT)acm.org), Jun 21 2002