A252875 Number of nX7 nonnegative integer arrays with upper left 0 and lower right n+7-4 and value increasing by 0 or 1 with every step right or down.
15, 211, 1948, 12686, 64920, 277585, 1030330, 3407823, 10237249, 28340232, 73128376, 177500233, 408299906, 895580310, 1882850350, 3810729118, 7452433875, 14127861337, 26034391284, 46747817584, 81967052716, 140602733711
Offset: 1
Keywords
Examples
Some solutions for n=3 ..0..0..1..1..2..3..4....0..1..2..3..4..4..4....0..1..2..3..3..4..5 ..1..1..2..2..3..4..5....1..2..3..4..4..5..5....1..2..2..3..4..5..6 ..2..2..2..3..4..5..6....1..2..3..4..5..5..6....1..2..3..4..5..5..6
Links
- R. H. Hardin, Table of n, a(n) for n = 1..210
Formula
Empirical: a(n) = (1/660441600)*n^14 + (1/9434880)*n^13 + (1/311850)*n^12 + (283/4989600)*n^11 + (23/34560)*n^10 + (5/896)*n^9 + (55843/1587600)*n^8 + (153793/907200)*n^7 + (4422487/7257600)*n^6 + (1152217/725760)*n^5 + (14953/4800)*n^4 + (834067/302400)*n^3 + (46071121/16816800)*n^2 - (359/17160)*n + 4
Comments