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A224276 Number of nX3 0..3 arrays with diagonals and rows unimodal and antidiagonals nondecreasing.

%I A224276 #6 Jul 23 2025 05:03:50
%S A224276 50,984,13683,186516,2596992,37128051,537465766,7804602744,
%T A224276 113382138975,1646661944858,23908590491858,347099092628781,
%U A224276 5038892410726190,73149786094975076,1061918636087967819,15415943271255819642
%N A224276 Number of nX3 0..3 arrays with diagonals and rows unimodal and antidiagonals nondecreasing.
%C A224276 Column 3 of A224281
%H A224276 R. H. Hardin, <a href="/A224276/b224276.txt">Table of n, a(n) for n = 1..210</a>
%F A224276 Empirical: a(n) = 20*a(n-1) -70*a(n-2) -211*a(n-3) +192*a(n-4) +15174*a(n-5) -36608*a(n-6) -83340*a(n-7) +59774*a(n-8) +2310958*a(n-9) -3620776*a(n-10) -5846720*a(n-11) +390652*a(n-12) +87932540*a(n-13) -70516876*a(n-14) +46329332*a(n-15) +7472696*a(n-16) -557612816*a(n-17) +319521288*a(n-18) -63018416*a(n-19) +17463360*a(n-20) +1046997696*a(n-21) -323677440*a(n-22) -14515200*a(n-23) -56540160*a(n-24) -635904000*a(n-25) for n>26
%e A224276 Some solutions for n=3
%e A224276 ..1..3..2....0..0..2....3..1..1....3..2..1....1..2..0....0..2..1....0..0..0
%e A224276 ..3..3..0....1..3..0....3..1..0....3..3..1....2..0..0....2..1..1....1..2..0
%e A224276 ..3..3..0....3..2..1....2..1..0....3..1..0....2..2..0....2..3..1....2..2..3
%K A224276 nonn
%O A224276 1,1
%A A224276 _R. H. Hardin_ Apr 02 2013