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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.

A213957 Number of n X n 0..3 matrices with row and column i=1..n having sum <= i*3.

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%I A213957 #6 Jun 02 2025 08:04:14
%S A213957 4,120,32060,74323976,1494988224948,261421322089741976,
%T A213957 398278555474658144086480,5298226825488439815883527067288
%N A213957 Number of n X n 0..3 matrices with row and column i=1..n having sum <= i*3.
%C A213957 Column 3 of A213962
%e A213957 Some solutions for n=4
%e A213957 ..0..0..1..2....1..0..0..0....3..0..0..0....3..0..0..0....3..0..0..0
%e A213957 ..0..3..3..0....0..3..1..2....0..1..1..1....0..3..3..0....0..2..2..0
%e A213957 ..1..0..1..2....1..0..1..3....0..1..2..3....0..1..3..3....0..3..1..3
%e A213957 ..1..1..0..0....1..3..3..1....0..1..2..0....0..1..1..1....0..0..3..3
%K A213957 nonn
%O A213957 1,1
%A A213957 _R. H. Hardin_ Jun 28 2012

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