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 A227769 #7 Jul 30 2013 15:13:21 %S A227769 6,20,252,468996,0,0,0 %N A227769 First (n+1)-fold perfect number divided by first n-fold perfect number, or 0 if the quotient is not an integer. %C A227769 The first n-fold perfect numbers are A007539 = 1, 6, 120, 30240, 14182439040, 154345556085770649600, ... %C A227769 For additional comments, references, links, and crossrefs, see A007539 and A227765. %F A227769 a(n) = A007539(n+1)/A007539(n) if n < 5. %e A227769 The first 4-fold and 5-fold perfect numbers are A007539(4) = 30240 and A007539(5) = 14182439040, and 14182439040/30240 = 468996 is an integer, so a(4) = 468996. %Y A227769 Cf. A007539, A227765, A227766, A227767, A227768. %K A227769 nonn %O A227769 1,1 %A A227769 _Jonathan Sondow_, Jul 30 2013