A252872 Number of n X 4 nonnegative integer arrays with upper left 0 and lower right n+4-4 and value increasing by 0 or 1 with every step right or down.

3, 26, 153, 615, 1953, 5281, 12686, 27805, 56624, 108549, 197804, 345216, 580452, 944778, 1494415, 2304572, 3474241, 5131844, 7441827, 10612301, 14903835, 20639511, 28216356, 38118271, 50930582, 67356343, 88234526, 114560238

Offset: 1

Author

R. H. Hardin, Dec 24 2014

Keywords

• nonn

Examples

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

Links

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

Crossrefs

Column 4 of A252876.

Formula

Empirical: a(n) = (1/8064)*n^8 + (1/288)*n^7 + (103/2880)*n^6 + (17/90)*n^5 + (655/1152)*n^4 + (331/288)*n^3 - (677/1120)*n^2 - (41/120)*n + 2.

Empirical: G.f.: -x*(3-x+27*x^2-78*x^3+120*x^4-110*x^5+59*x^6-17*x^7+2*x^8) / (x-1)^9. - R. J. Mathar, Nov 23 2015