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

1,1

Links

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

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

Example

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

Crossrefs

Column 4 of A252876.

Sequence in context: A034495 A034493 A265467 * A121626 A038697 A226351

Adjacent sequences: A252869 A252870 A252871 * A252873 A252874 A252875

Keyword

nonn

Author

R. H. Hardin, Dec 24 2014

Status

approved