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 A151687 #6 Jan 04 2021 03:48:33
%S A151687 0,1,2,3,3,3,5,6,4,3,5,6,6,8,11,10,5,3,5,6,6,8,11,10,7,8,11,12,14,19,
%T A151687 21,15,6,3,5,6,6,8,11,10,7,8,11,12,14,19,21,15,8,8,11,12,14,19,21,17,
%U A151687 15,19,23,26,33,40,36,21,7,3,5,6,6,8,11,10,7,8,11,12,14,19,21,15,8,8
%N A151687 G.f.: x + x^2 * Product_{n>=0} (1 + x^(2^n-1) + x^(2^n)).
%C A151687 Apart from initial terms and offset, same as A160573, but has a slightly nice recurrence.
%F A151687 a(0) = 0, a(2^k) = k+1; for n >= 3, if n = 2^i + j, 1 <= j < 2^i, a(n) = a(j) + a(j+1).
%p A151687 G:= x + x^2 * mul( 1 + x^(2^n-1) + x^(2^n), n=0..20);
%Y A151687 Rows of triangle in A118977 converge to this.
%K A151687 nonn
%O A151687 0,3
%A A151687 _N. J. A. Sloane_, Jun 03 2009