A252975 Number of nX7 nonnegative integer arrays with upper left 0 and lower right n+7-5 and value increasing by 0 or 1 with every step right or down.

20, 483, 8694, 112877, 1100210, 8528422, 54926890, 303382053, 1471499970, 6383377435, 25130419118, 90859574359, 304675148476, 955390407363, 2821209579406, 7892066379909, 21022079637900, 53557533613173

Offset: 1

Author

R. H. Hardin, Dec 25 2014

Keywords

• nonn

Comments

Column 7 of A252976

Examples

			Some solutions for n=4
..0..1..2..3..3..3..4....0..1..1..2..2..3..4....0..0..1..2..3..3..3
..1..2..2..3..3..3..4....1..1..2..3..3..4..5....1..1..1..2..3..4..4
..2..2..2..3..3..4..5....2..2..3..3..4..5..6....1..1..2..2..3..4..5
..2..3..3..4..4..5..6....2..3..4..4..5..6..6....1..1..2..3..4..5..6
		

Links

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

Formula

Empirical: a(n) = (491/510909421717094400)*n^21 + (491/4054836680294400)*n^20 + (31237/4561691265331200)*n^19 + (16931/72754246656000)*n^18 + (6860417/1280474741145600)*n^17 + (5620079/62768369664000)*n^16 + (28238557/24715045555200)*n^15 + (460147/39626496000)*n^14 + (1994012479/20542375526400)*n^13 + (9803403773/14485008384000)*n^12 + (2842330237/724250419200)*n^11 + (22704330871/1207084032000)*n^10 + (117780405261823/1581762915532800)*n^9 + (1372309011587/5706215424000)*n^8 + (17399771450683/28245766348800)*n^7 + (29498769372031/23538138624000)*n^6 + (57797311549729/26676557107200)*n^5 + (6071375333369/2020951296000)*n^4 + (7008309815167/1119943843200)*n^3 + (375662307017/83805321600)*n^2 + (152121493/25865840)*n - 4