A225340 - cp's OEIS frontend

A225340 Number of nX4 -1,1 arrays such that the sum over i=1..n,j=1..4 of i*x(i,j) is zero, the sum of x(i,j) is zero, and rows are nondecreasing (number of ways to distribute 4-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	9
5	31
6	107
7	395
8	1525
9	6095
10	24893
11	103583
12	437763
13	1874497
14	8116459
15	35485099
16	156453779
17	694956997
18	3107415563
19	13976787615
20	63201012187
21	287163163723
22	1310481411725
23	6004334305049
24	27611237977705
25	127399143883589

[1, 1, 3, 9, 31, 107, 395, 1525, 6095, 24893, 103583, 437763, 1874497, 8116459, 35485099, 156453779, 694956997, 3107415563, 13976787615, 63201012187, 287163163723, 1310481411725, 6004334305049, 27611237977705, 127399143883589]

cp's OEIS Frontend

A225340 Number of nX4 -1,1 arrays such that the sum over i=1..n,j=1..4 of i*x(i,j) is zero, the sum of x(i,j) is zero, and rows are nondecreasing (number of ways to distribute 4-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