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Number of 9-colorings of an n X n grid, up to rotational symmetry.
3

%I #9 Apr 14 2021 22:28:32

%S 1,9,1665,96870249,463255057977921,179474496923598616041129,

%T 5632099886234793640483695986653185,

%U 14316042242555870306568544190208626253583093449,2947546144434645792880218215353988087374626027116634833972481

%N Number of 9-colorings of an n X n grid, up to rotational symmetry.

%H Andrew Howroyd, <a href="/A047944/b047944.txt">Table of n, a(n) for n = 0..25</a>

%F a(n) = (m^(n^2) + 2 m^((n^2 + 3 (n mod 2))/4) + m^((n^2 + (n mod 2))/2))/4, with m = 9.

%Y Column k=9 of A343095.

%Y Cf. A047937.

%K nonn

%O 0,2

%A _Rob Pratt_

%E Terms a(8) and beyond from _Andrew Howroyd_, Apr 14 2021