A252970 Number of nX2 nonnegative integer arrays with upper left 0 and lower right n+2-5 and value increasing by 0 or 1 with every step right or down

0, 0, 1, 13, 61, 192, 483, 1050, 2058, 3732, 6369, 10351, 16159, 24388, 35763, 51156, 71604, 98328, 132753, 176529, 231553, 299992, 384307, 487278, 612030, 762060, 941265, 1153971, 1404963, 1699516, 2043427, 2443048, 2905320, 3437808, 4048737

Offset

1,4

Comments

Column 2 of A252976

Links

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

Formula

Empirical: a(n) = (1/720)*n^6 + (7/240)*n^5 - (1/144)*n^4 - (31/48)*n^3 + (271/180)*n^2 - (53/60)*n = n*(n-1)*(n-2)*(n^3+24*n^2+65*n-318)/720.

Empirical: G.f.: -x^3*(1+6*x-9*x^2+3*x^3) / (x-1)^7 . - R. J. Mathar, Nov 23 2015

Example

Some solutions for n=4
..0..0....0..0....0..0....0..0....0..0....0..0....0..1....0..0....0..1....0..1
..0..1....0..0....0..0....1..1....0..0....0..1....0..1....0..0....1..1....0..1
..0..1....0..0....0..0....1..1....1..1....0..1....0..1....0..1....1..1....0..1
..1..1....0..1....1..1....1..1....1..1....0..1....0..1....0..1....1..1....1..1

Crossrefs

Sequence in context: A357964 A353223 A302560 * A047673 A231800 A141725

Adjacent sequences: A252967 A252968 A252969 * A252971 A252972 A252973

Keyword

nonn

Author

R. H. Hardin, Dec 25 2014

Status

approved