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%I #13 Jun 18 2023 01:48:30
%S 1,4,70,65824,1073758336,281474993496064,1180591620734591303680,
%T 79228162514264619068554215424,85070591730234615870455337878516924416,
%U 1461501637330902918203686041642102636484130504704,401734511064747568885490523085607563280607806359022338048000
%N Number of 4-colorings of an n X n grid, up to rotational symmetry.
%H Andrew Howroyd, <a href="/A047939/b047939.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 = 4.
%Y Column k=4 of A343095.
%Y Cf. A054751, A047937.
%K nonn
%O 0,2
%A _Rob Pratt_
%E Terms a(10) and beyond from _Andrew Howroyd_, Apr 14 2021
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