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 A130533 #6 Mar 31 2012 14:42:50 %S A130533 0,0,2,6,13,9,2,19,2,19,2,3,4,37,8,43,47,47,53,2,6,59,61,8,71,6,79,2, %T A130533 5,83,89,2,3,12,101,107,4,3,3,2,11 %N A130533 a(n) = smallest k such that A001358(n+1) = A001358(n) + (A001358(n) mod k), or 0 if no such k exists. %C A130533 a(n) is the "weight" of semiprimes. %C A130533 The decomposition of semiprimes into weight * level + gap is A001358(n) = a(n) * A184729(n) + A065516(n) if a(n) > 0. %H A130533 Remi Eismann, <a href="/A130533/b130533.txt">Table of n, a(n) for n=1..9999</a> %e A130533 For n = 1 we have A001358(n) = 4, A001358(n+1) = 6; there is no k such that 6 - 4 = 2 = (4 mod k), hence a(1) = 0. %e A130533 For n = 3 we have A001358(n) = 9, A001358(n+1) = 10; 2 is the smallest k such that 10 - 9 = 1 = (9 mod k), hence a(3) = 2. %e A130533 For n = 19 we have A001358(n) = 55, A001358(n+1) = 57; 53 is the smallest k such that 57 - 55 = 2 = (55 mod k), hence a(19) = 53. %Y A130533 Cf. A001358, A065516, A184729, A184728, A117078, A117563, A001223, A118534. %K A130533 nonn %O A130533 1,3 %A A130533 _Rémi Eismann_, Aug 16 2007 - Jan 20 2011