A223920 Number of 3Xn 0..2 arrays with rows and antidiagonals unimodal and columns nondecreasing

10, 100, 666, 3311, 13347, 45988, 140236, 387671, 988447, 2354539, 5291652, 11307388, 23115717, 45438234, 86243127, 158615577, 283521156, 493809754, 839915122, 1397838161, 2280164963, 3651068140, 5746477482, 8900889311

Offset

1,1

Comments

Row 3 of A223918

Links

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

Formula

Empirical: a(n) = (1/19160064)*n^12 + (5/3193344)*n^11 + (1627/43545600)*n^10 + (257/483840)*n^9 + (2309/414720)*n^8 + (19319/483840)*n^7 + (8701321/43545600)*n^6 + (971137/1451520)*n^5 + (3369229/2177280)*n^4 + (294809/120960)*n^3 + (652717/237600)*n^2 + (521/385)*n + 1

Example

Some solutions for n=3
..0..0..1....0..1..0....0..1..1....2..0..0....1..0..0....0..0..1....0..1..1
..2..1..1....1..1..1....1..1..2....2..2..1....1..2..0....0..1..2....1..1..1
..2..2..1....1..2..2....1..2..2....2..2..2....1..2..2....1..1..2....1..1..2

Crossrefs

Sequence in context: A208074 A092707 A224263 * A223865 A366669 A293890

Adjacent sequences: A223917 A223918 A223919 * A223921 A223922 A223923

Keyword

nonn

Author

R. H. Hardin Mar 29 2013

Status

approved