A145241 1/4 of the number of 4-colorings of an n X n array symmetric about both diagonal and antidiagonal.

1, 3, 27, 189, 3969, 64827, 3179169, 121272795, 13891861179, 1237840901829, 331231632520635, 68946329439933309, 43098014529769439457, 20956433266778185286019, 30601694853748262964093129

Offset

1,2

Links

Table of n, a(n) for n=1..15.

Crossrefs

Sequence in context: A248225 A251732 A385034 * A118996 A267947 A230170

Adjacent sequences: A145238 A145239 A145240 * A145242 A145243 A145244

Keyword

nonn

Author

R. H. Hardin, Oct 05 2008

Status

approved