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 A101555 #8 May 24 2018 08:03:38
%S A101555 0,1,4,12,37,111,333,1000,3001,9003,27009,81028,243084,729253,2187760,
%T A101555 6563280,19689841,59069523,177208569,531625708,1594877124,4784631373,
%U A101555 14353894120,43061682360,129185047080,387555141241,1162665423724
%N A101555 Convolution of A010060 and A000244.
%C A101555 A Thue-Morse convolution.
%H A101555 G. C. Greubel, <a href="/A101555/b101555.txt">Table of n, a(n) for n = 0..1000</a>
%F A101555 a(n) = Sum_{k=0..n} A010060(n-k) * 3^k.
%t A101555 Table[Sum[ThueMorse[n - k]*3^k, {k, 0, n}], {n, 0, 100}] (* _G. C. Greubel_, May 23 2018 *)
%Y A101555 Cf. A000244, A010060.
%K A101555 easy,nonn
%O A101555 0,3
%A A101555 _Paul Barry_, Dec 06 2004