A252972 Number of nX4 nonnegative integer arrays with upper left 0 and lower right n+4-5 and value increasing by 0 or 1 with every step right or down.
1, 13, 153, 1236, 6997, 30802, 112877, 359550, 1024773, 2667554, 6438457, 14575914, 31230978, 63789948, 124931040, 235737421, 430298389, 762367687, 1314817821, 2212837300, 3642069999, 5873199042, 9294839027, 14457028052, 22128113529
Offset: 1
Keywords
Examples
Some solutions for n=4 ..0..1..1..1....0..1..2..3....0..0..0..1....0..1..2..2....0..0..1..2 ..0..1..1..1....0..1..2..3....1..1..1..2....0..1..2..2....0..1..2..2 ..0..1..2..2....1..2..2..3....2..2..2..2....1..1..2..3....1..2..2..2 ..0..1..2..3....1..2..3..3....2..2..3..3....1..2..2..3....2..3..3..3
Links
- R. H. Hardin, Table of n, a(n) for n = 1..210
Formula
Empirical: a(n) = (29/479001600)*n^12 + (29/8870400)*n^11 + (3083/43545600)*n^10 + (233/290304)*n^9 + (73739/14515200)*n^8 + (48151/2419200)*n^7 + (2494049/43545600)*n^6 + (31657/483840)*n^5 - (1169489/10886400)*n^4 - (1024151/1814400)*n^3 + (2116423/831600)*n^2 - (601/27720)*n - 1
Comments