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 A247106 #15 Nov 19 2014 08:39:44
%S A247106 5,2100,457712,112269228,28477328812,7318410460100,1890316186147022,
%T A247106 488986474759870194,126570653719713453566,32767699501924700122356,
%U A247106 8483817993681247935283336,2196573666944370207848161336,568727175315063817973036015946
%N A247106 Number of paths joining opposite corners of an n X 4 grid with every vertex appearing at most twice in the path.
%C A247106 Limit n->infinity a(n)^(1/n) = 258.91660336499804152326399147605283475710016... . - _Vaclav Kotesovec_, Nov 19 2014
%H A247106 Muhammad Kholilurrohman, <a href="/A247106/b247106.txt">Table of n, a(n) for n = 1..100</a>
%e A247106 For n = 1 corresponds to a straight line graph with vertices {1,2,3,4}. Then the a(1) = 5 solutions are 1234, 121234, 123234, 123434, and 12123434.
%Y A247106 Cf. A239688, A247070.
%K A247106 nonn
%O A247106 1,1
%A A247106 _Muhammad Kholilurrohman_, Nov 18 2014