A225342 - cp's OEIS frontend

A225342 Number of nX6 -1,1 arrays such that the sum over i=1..n,j=1..6 of i*x(i,j) is zero, the sum of x(i,j) is zero, and rows are nondecreasing (number of ways to distribute 6-across galley oarsmen left-right at n fore-aft positions so that there are no turning moments on the ship).

n	a(n)
1	1
2	1
3	3
4	17
5	81
6	397
7	2073
8	11291
9	63121
10	360909
11	2102597
12	12439855
13	74561687
14	451920441
15	2765717847
16	17069622035
17	106139191511
18	664358517275
19	4183117802521
20	26479526009223
21	168426949915891
22	1076002461947039

[1, 1, 3, 17, 81, 397, 2073, 11291, 63121, 360909, 2102597, 12439855, 74561687, 451920441, 2765717847, 17069622035, 106139191511, 664358517275, 4183117802521, 26479526009223, 168426949915891, 1076002461947039]

cp's OEIS Frontend

A225342 Number of nX6 -1,1 arrays such that the sum over i=1..n,j=1..6 of i*x(i,j) is zero, the sum of x(i,j) is zero, and rows are nondecreasing (number of ways to distribute 6-across galley oarsmen left-right at n fore-aft positions so that there are no turning moments on the ship).

Table of values

List of values