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A223866 Number of 3Xn 0..3 arrays with rows and antidiagonals unimodal and columns nondecreasing 1
20, 400, 4884, 41682, 273959, 1477240, 6818350, 27746619, 101698292, 341120712, 1060013078, 3081189588, 8443340635, 21952389700, 54443494785, 129382581759, 295772387822, 652604111790, 1393875593290, 2889329636208, 5825806879833 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 3 of A223864

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210

FORMULA

Empirical: a(n) = (1/3629463552000)*n^18 + (7/403273728000)*n^17 + (667/951035904000)*n^16 + (3281/174356582400)*n^15 + (148069/402361344000)*n^14 + (1366301/249080832000)*n^13 + (3748907/57480192000)*n^12 + (1190879/1916006400)*n^11 + (344761547/73156608000)*n^10 + (684241027/24385536000)*n^9 + (104051693257/804722688000)*n^8 + (54794329/119750400)*n^7 + (786440609/628992000)*n^6 + (81330893999/31135104000)*n^5 + (895703793151/217945728000)*n^4 + (8582457311/1816214400)*n^3 + (317136049/79168320)*n^2 + (10267897/6126120)*n + 1

EXAMPLE

Some solutions for n=3

..0..1..2....0..1..0....3..2..0....0..0..0....0..0..0....0..2..0....0..0..0

..2..2..2....0..3..0....3..2..0....1..3..1....3..1..0....0..2..0....1..1..0

..2..3..3....1..3..2....3..3..0....3..3..2....3..3..1....1..3..1....3..3..1

CROSSREFS

Sequence in context: A224174 A206891 A188759 * A207091 A223988 A189698

Adjacent sequences:  A223863 A223864 A223865 * A223867 A223868 A223869

KEYWORD

nonn

AUTHOR

R. H. Hardin Mar 28 2013

STATUS

approved

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Last modified June 1 07:40 EDT 2020. Contains 334759 sequences. (Running on oeis4.)