A145240 1/4 of the number of 4-colorings of an n X n array symmetric about main diagonal.

1, 9, 189, 9261, 1059723, 283237101, 176834417193, 257902966790973, 878667709192614747, 6993173781818645577597, 130018879726411743573963849, 5647047812461224621198055679517, 572953904651272394794692262471961499

Offset

1,2

Links

Table of n, a(n) for n=1..13.

Crossrefs

Sequence in context: A347855 A249932 A278751 * A113564 A157387 A218422

Adjacent sequences: A145237 A145238 A145239 * A145241 A145242 A145243

Keyword

nonn

Author

R. H. Hardin, Oct 05 2008

Status

approved