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 A137343 #8 Apr 20 2015 12:42:10 %S A137343 1,12,1296,505536,679848192,3248147205120,57637071142391808, %T A137343 3930578658351563587584,1050888530707010579202637824, %U A137343 1112792971262327168651248131637248 %N A137343 Number of elements of length n with respect to the natural metric in the special group of rational series over the finite field F_2 in two non-commuting variables. %H A137343 Roland Bacher, Apr 08 2008, <a href="/A137343/b137343.txt">Table of n, a(n) for n = 0..14</a> %H A137343 R. Bacher, <a href="http://arxiv.org/abs/0804.1092">The special subgroup of invertible non-commutative rational power series as a metric group</a>, arXiv:0804.1092 %F A137343 The reference contains a somewhat complicated formula. %K A137343 nonn %O A137343 0,2 %A A137343 _Roland Bacher_, Apr 08 2008