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A201491 Number of nX3 zero-sum -2..2 arrays with rows and columns lexicographically nondecreasing.

%I A201491 #7 Jul 22 2025 16:16:15
%S A201491 5,226,9331,301432,7798656,168357815,3127432827,51118964623,
%T A201491 747555368709,9907361072523,120219907134113,1346895312283777,
%U A201491 14030077787811997,136685387878719346,1251770455347161910,10823892860244631974
%N A201491 Number of nX3 zero-sum -2..2 arrays with rows and columns lexicographically nondecreasing.
%C A201491 Column 3 of A201496
%H A201491 R. H. Hardin, <a href="/A201491/b201491.txt">Table of n, a(n) for n = 1..90</a>
%e A201491 Some solutions for n=3
%e A201491 .-2..1..1...-2.-1.-1...-1.-1..1...-2.-1..2...-2..1..2...-2.-1..2...-2..0..0
%e A201491 .-2..1..1....0..0..0....1..2.-2...-1..0..1....0.-1..1...-2..1..1...-1.-1.-1
%e A201491 ..0.-2..2....2..0..2....2..0.-2....1.-1..1....2.-1.-2...-1..1..1....1..2..2
%K A201491 nonn
%O A201491 1,1
%A A201491 _R. H. Hardin_ Dec 02 2011