A247106 Number of paths joining opposite corners of an n X 4 grid with every vertex appearing at most twice in the path.

5, 2100, 457712, 112269228, 28477328812, 7318410460100, 1890316186147022, 488986474759870194, 126570653719713453566, 32767699501924700122356, 8483817993681247935283336, 2196573666944370207848161336, 568727175315063817973036015946

Offset: 1

Author

Muhammad Kholilurrohman, Nov 18 2014

Keywords

• nonn

Comments

Limit n->infinity a(n)^(1/n) = 258.91660336499804152326399147605283475710016... . - Vaclav Kotesovec, Nov 19 2014

Examples

			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.
		

Links

• Muhammad Kholilurrohman, Table of n, a(n) for n = 1..100

Crossrefs

Cf. A239688, A247070.