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 A229650 #14 Oct 22 2015 14:49:03
%S A229650 1,4,28,232,2092,19864,195352,1970896,20275660,211823836,2240798048,
%T A229650 23951367224,258257552968,2805581350056,30676425237024,
%U A229650 337324008602512,3727882769574860,41381900166952348,461201577710442388,5158610797198820800
%N A229650 Cogrowth function of the group Baumslag-Solitar(8,8).
%C A229650 a(n) is the number of words of length 2n in the letters a,a^{-1},t,t^{-1} that equal the identity of the group BS(8,8)=<a,t | ta^8=a^8t>.
%H A229650 Murray Elder, <a href="/A229650/b229650.txt">Table of n, a(n) for n = 0..50</a>
%H A229650 M. Elder, A. Rechnitzer, E. J. Janse van Rensburg, T. Wong, <a href="http://arxiv.org/abs/1309.4184">The cogrowth series for BS(N,N) is D-finite</a>
%H A229650 <a href="/index/Gre#groups">Index entries for sequences related to groups</a>
%e A229650 For n=1 there are 4 words of length 2 equal to the identity: aa^{-1}, a^{-1}a, tt^{-1}, t^{-1}t.
%Y A229650 The cogrowth sequences for BS(N,N) for N = 1..10 are A002894, A229644, A229645, A229646, A229647, A229648, A229649, A229650, A229651, A229652.
%K A229650 nonn,walk
%O A229650 0,2
%A A229650 _Murray Elder_, Sep 27 2013