A224376 Number of 4 X n 0..2 arrays with rows unimodal and antidiagonals nondecreasing.

81, 1944, 15540, 77793, 311367, 1092281, 3518302, 10643789, 30548895, 83538706, 218139823, 544930741, 1304961768, 3002671615, 6654904188, 14242413828, 29504608642, 59301307852, 115889490174, 220645337145, 410024971049

Offset

1,1

Links

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

Formula

Empirical: a(n) = (1/106748928000)*n^16 + (1/1482624000)*n^15 + (7/266872320)*n^14 + (127/197683200)*n^13 + (315179/28740096000)*n^12 + (24499/177408000)*n^11 + (89507/65318400)*n^10 + (112109/9676800)*n^9 + (68633371/746496000)*n^8 + (11395841/16128000)*n^7 + (6723664007/1437004800)*n^6 + (295741651/13305600)*n^5 + (262119224347/5189184000)*n^4 - (16331232329/1297296000)*n^3 + (12600631/343200)*n^2 + (38790413/360360)*n - 166 for n>2.

Example

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

Crossrefs

Row 4 of A224374.

Sequence in context: A233371 A225019 A224312 * A237957 A238038 A236088

Adjacent sequences: A224373 A224374 A224375 * A224377 A224378 A224379

Keyword

nonn

Author

R. H. Hardin, Apr 05 2013

Status

approved