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 A109915 #12 Jun 24 2025 03:30:09 %S A109915 1,1,4,1,6,1,720,90,10,1,12,1,3360,240,16,1,18,1,9240,462,22,1, %T A109915 11793600,491400,19656,756,28,1,30,1,45239040,1413720,42840,1260,36,1, %U A109915 59280,1560,40,1,42,1,91080,2070,46,1,311875200,6497400,132600,2652 %N A109915 Product of all composite numbers k such that n<k<prime(r) where prime(r-1)<=n, or 1 if this set of k is empty. %C A109915 All terms that differ from 1 have the format A092435(i+1)/A092435(i). - _R. J. Mathar_, Aug 15 2007 %H A109915 Robert Israel, <a href="/A109915/b109915.txt">Table of n, a(n) for n = 1..10000</a> %e A109915 a(7) = 8*9*10 = 720. %p A109915 A109915 := proc(n) local a,rm1,k; a := 1: rm1 := numtheory[pi](n) ; for k from n+1 to ithprime(rm1+1) do if not isprime(k) then a := a*k; fi; od: RETURN(a) ; end: seq(A109915(n),n=1..50) ; # _R. J. Mathar_, Aug 15 2007 %Y A109915 Cf. A109914. %K A109915 nonn,look %O A109915 1,3 %A A109915 _Amarnath Murthy_, Jul 16 2005 %E A109915 Corrected and extended by _R. J. Mathar_, Aug 15 2007