A224174 Number of 3 X n 0..3 arrays with rows, diagonals 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

Author

R. H. Hardin, Mar 31 2013

Keywords

• nonn

Examples

			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
		

Links

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

Crossrefs

Row 3 of A224173.

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.

Extensions

Name corrected by Andrew Howroyd, Mar 18 2025