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A223764
Number of n X 2 0..1 arrays with rows, columns and antidiagonals unimodal and diagonals nondecreasing.
4
4, 12, 28, 56, 101, 169, 267, 403, 586, 826, 1134, 1522, 2003, 2591, 3301, 4149, 5152, 6328, 7696, 9276, 11089, 13157, 15503, 18151, 21126, 24454, 28162, 32278, 36831, 41851, 47369, 53417, 60028, 67236, 75076, 83584, 92797, 102753, 113491, 125051
OFFSET
1,1
COMMENTS
Column 2 of A223770.
LINKS
FORMULA
Empirical: a(n) = (1/24)*n^4 + (1/4)*n^3 + (35/24)*n^2 + (5/4)*n + 1.
Conjectures from Colin Barker, Feb 21 2018: (Start)
G.f.: x*(2 - 2*x + x^2)^2 / (1 - x)^5.
a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5) for n>5.
(End)
EXAMPLE
Some solutions for n=3:
..0..0....0..0....0..0....1..0....1..1....0..0....0..1....0..1....0..0....0..1
..0..0....0..0....1..1....0..1....0..1....1..0....1..1....0..0....1..0....0..1
..1..1....0..1....1..1....0..0....0..1....0..1....0..1....0..0....1..1....1..0
CROSSREFS
Cf. A223770.
Sequence in context: A161216 A085622 A011940 * A102653 A102650 A011939
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 27 2013
STATUS
approved