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This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A216456 Number of horizontal, diagonal and antidiagonal neighbor colorings of the even squares of an n X n array with new integer colors introduced in row major order.

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%I A216456 #7 Jul 22 2025 23:31:44
%S A216456 1,1,7,203,580479,6423127757,22530453266592757
%N A216456 Number of horizontal, diagonal and antidiagonal neighbor colorings of the even squares of an n X n array with new integer colors introduced in row major order.
%C A216456 Diagonal of A216460
%e A216456 Some solutions for n=4
%e A216456 ..0..x..1..x....0..x..1..x....0..x..1..x....0..x..1..x....0..x..1..x
%e A216456 ..x..2..x..3....x..2..x..3....x..2..x..3....x..2..x..3....x..2..x..3
%e A216456 ..3..x..1..x....3..x..4..x....4..x..0..x....3..x..4..x....0..x..1..x
%e A216456 ..x..4..x..2....x..5..x..2....x..1..x..3....x..1..x..2....x..4..x..0
%K A216456 nonn
%O A216456 1,3
%A A216456 _R. H. Hardin_ Sep 07 2012

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