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 A161360 #4 Mar 15 2015 09:47:59 %S A161360 2,4,9,5,8,0,6,5,1,4,0,5,9,8,3,8,2,7,2,7,7,4,9,7,9,2,0,4,9,3,0,1,5,3, %T A161360 4,3,7,2,6,1,0,3,7,9,3,7,6,1,5,5,0,7,7,9,6,3,9,6,9,1,6,5,3,8,9,5,1,3, %U A161360 5,7,2,2,2,6,4,9,6,5,6,5,6,9,0,4,5,5,5,7,0,3,4,8,5,6,1,3,5,4,0,0,1,6,2,5,2 %N A161360 Decimal expansion of Product_p p#/(p#-1). %C A161360 By p# we mean the primorial number which is the product of the primes less than or equal to p. %F A161360 This number is equal to Sum_k 1/A025487(k). %e A161360 2/1 * 6/5 * 30/29 * ... = 2.495806514059838272774979204930153... %t A161360 RealDigits[Times@@(#/(#-1)&/@Rest[FoldList[Times,1,Prime[Range[100]]]]), 10,120][[1]] (* _Harvey P. Dale_, Mar 15 2015 *) %o A161360 (PARI) h(n)=local(p,pl,r);p=2;pl=1;r=1.;while(p<n,pl*=p;r/=(1-1./pl);p=nextprime(p+1));r %Y A161360 Cf. A002110, A034386, A025487, A064648. %K A161360 cons,nonn %O A161360 1,1 %A A161360 _Franklin T. Adams-Watters_, Jun 07 2009