A224174 Number of 3 X n 0..3 arrays with rows and antidiagonals unimodal and columns nondecreasing.

20, 400, 4739, 38561, 242114, 1253770, 5588411, 22075529, 78911656, 259222964, 791787532, 2269535600, 6149706181, 15847969147, 39036356744, 92295124070, 210220319550, 462719488690, 986952548003, 2044823738533, 4124042889158

Offset

1,1

Comments

Row 3 of A224173.

Links

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

Formula

Empirical: a(n) = (1/3629463552000)*n^18 + (1/80654745600)*n^17 + (5153/10461394944000)*n^16 + (33323/2615348736000)*n^15 + (186871/747242496000)*n^14 + (566921/149448499200)*n^13 + (390989/8211456000)*n^12 + (13776731/28740096000)*n^11 + (283859867/73156608000)*n^10 + (359930911/14631321600)*n^9 + (13824123559/114960384000)*n^8 + (6442744127/14370048000)*n^7 + (11719345643/8895744000)*n^6 + (10048449577/3736212480)*n^5 + (1016995336979/217945728000)*n^4 + (32943067909/9081072000)*n^3 + (5801778061/735134400)*n^2 - (393478/36465)*n + 10.

Example

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

Crossrefs

Cf. A224173.

Sequence in context: A206782 A188519 A189260 * A206891 A188759 A223866

Adjacent sequences: A224171 A224172 A224173 * A224175 A224176 A224177

Keyword

nonn

Author

R. H. Hardin, Mar 31 2013

Status

approved