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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.

A221665 Sum of neighbor maps: number of nX4 binary arrays indicating the locations of corresponding elements equal to the sum mod 3 of their horizontal, diagonal and antidiagonal neighbors in a random 0..2 nX4 array.

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%I A221665 #5 Jul 23 2025 02:06:15
%S A221665 16,256,3772,63200,1048576,16777216,268281856,4294967296,68702508544,
%T A221665 1099511627776,17592133540864,281474976710656,4503599627370496
%N A221665 Sum of neighbor maps: number of nX4 binary arrays indicating the locations of corresponding elements equal to the sum mod 3 of their horizontal, diagonal and antidiagonal neighbors in a random 0..2 nX4 array.
%C A221665 Column 4 of A221666
%e A221665 Some solutions for n=3
%e A221665 ..0..1..0..0....0..1..1..0....0..1..0..0....1..1..0..0....0..0..0..1
%e A221665 ..1..0..1..1....1..1..0..1....1..1..0..0....0..0..0..1....0..0..0..1
%e A221665 ..0..1..0..1....1..1..0..1....0..1..1..0....1..1..1..1....1..1..0..0
%K A221665 nonn
%O A221665 1,1
%A A221665 _R. H. Hardin_ Jan 21 2013

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