A068257 1/7 the number of colorings of an n X n square array with 7 colors.

1, 186, 923526, 122408393436, 433110977725751106, 40908457493732914322944536, 103146129375410533061371714364918916, 6942544711174164051575906086886643368922134556, 12474132532762777585883439690925675118905860580968258566406

Offset: 1

Author

R. H. Hardin, Feb 24 2002

Keywords

• nonn

Links

• Jean-François Alcover, Table of n, a(n) for n = 1..13

Crossrefs

Main diagonal of A222340.

Cf. A068239-A068305, A000332, A002417, A027441, A182368, A182406.

Programs

Mathematica

A222340 = Cases[Import["https://oeis.org/A222340/b222340.txt", "Table"], {, }][[All, 2]];
a[n_] := A222340[[2 n^2 - 2 n + 1]];
Table[a[n], {n, 1, 13}] (* Jean-François Alcover, Sep 23 2019 *)

Extensions

a(7)-a(9) from Alois P. Heinz, Apr 27 2012