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 A134659 #10 Mar 17 2015 23:49:45
%S A134659 1,4,7,12,15,24,29,40,43,52,61,76,81,96,107,128,131,140,149,164,173,
%T A134659 200,215,248,253,268,283,308,319,352,373,416,419,428,437,452,461,488,
%U A134659 503,536,545,572,599,644,659,704,737,800,805,820,835,860,875,920,945,1000
%N A134659 Total number of odd coefficients in (1+x+x^2)^k for k=0,...,n.
%C A134659 a(n) = Sum_{k <= n} A071053(k)
%H A134659 N. J. A. Sloane, <a href="/A134659/b134659.txt">Table of n, a(n) for n = 0..16383</a>
%H A134659 S. R. Finch, P. Sebah and Z.-Q. Bai, <a href="http://arXiv.org/abs/0802.2654">Odd Entries in Pascal's Trinomial Triangle</a> (arXiv:0802.2654)
%H A134659 N. J. A. Sloane, <a href="http://arxiv.org/abs/1503.01168">On the Number of ON Cells in Cellular Automata</a>, arXiv:1503.01168, 2015
%t A134659 Sum[PolynomialMod[(1+x+x^2)^k, 2] /. x->1, {k, 0, n-1}]
%Y A134659 Cf. A001316, A006046, A027907, A071053.
%K A134659 nonn
%O A134659 0,2
%A A134659 _Steven Finch_, Jan 25 2008
%E A134659 Offset changed to 0 by _N. J. A. Sloane_, Feb 06 2015