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 A131470 #4 Oct 04 2012 16:12:59 %S A131470 2,3,2,5,3,4,3,9,5,6,4,7,5,5,4,17,9,10,7,11,8,8,6,13,9,9,7,10,8,8,7, %T A131470 33,17,18,12,19,13,13,10,21,14,15,11,15,12,12,10,25,17,17,13,18,14,14, %U A131470 12,19,15,15,12,16,13,13,11,65,33,34,23 %N A131470 a(n)=smallest number that gives a product with the sum of digits of n written in base 2 greater than n. %F A131470 Let sd2(n) the sum of digits of n written in base 2. Then a(n) =1 + Floor(n/sd2(n)). %e A131470 9 is written 1001 in base 2, then sd2(9)=2; 4*2<9<5*2; then (c,9)=5 %K A131470 easy,nonn,base %O A131470 1,1 %A A131470 Philippe LALLOUET (philip.lallouet(AT)wanadoo.fr), Jul 27 2007