login
A252871
Number of nX3 nonnegative integer arrays with upper left 0 and lower right n+3-4 and value increasing by 0 or 1 with every step right or down
2
1, 8, 44, 153, 413, 949, 1948, 3676, 6497, 10894, 17492, 27083, 40653, 59411, 84820, 118630, 162913, 220100, 293020, 384941, 499613, 641313, 814892, 1025824, 1280257, 1585066, 1947908, 2377279, 2882573, 3474143, 4163364, 4962698, 5885761, 6947392
OFFSET
1,2
COMMENTS
Column 3 of A252876
LINKS
FORMULA
Empirical: a(n) = (1/360)*n^6 + (1/20)*n^5 + (5/18)*n^4 + (1/3)*n^3 + (79/360)*n^2 - (113/60)*n + 2.
Empirical: G.f.: -x*(1+x+9*x^2-22*x^3+21*x^4-10*x^5+2*x^6) / (x-1)^7. - R. J. Mathar, Nov 23 2015
EXAMPLE
Some solutions for n=3
..0..1..1....0..1..1....0..1..2....0..0..0....0..1..1....0..0..1....0..1..1
..0..1..1....1..1..1....0..1..2....1..1..1....1..2..2....1..1..1....1..1..1
..1..2..2....1..1..2....1..2..2....1..2..2....2..2..2....1..2..2....2..2..2
CROSSREFS
Sequence in context: A261996 A036464 A000938 * A307044 A165618 A250285
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 24 2014
STATUS
approved