A225309 - cp's OEIS frontend

A225309 Number of nX8 -1,1 arrays such that the sum over i=1..n,j=1..8 of i*x(i,j) is zero and rows are nondecreasing (ways to put 8 thrusters pointing east or west at each of n positions 1..n distance from the hinge of a south-pointing gate without turning the gate).

n	a(n)
1	1
2	5
3	27
4	175
5	1165
6	8221
7	60007
8	449693
9	3437315
10	26700429
11	210147859
12	1672294243
13	13432357463
14	108761156653
15	886785526897
16	7274670122017
17	59999774031797
18	497244626964801
19	4138638973241695
20	34580160863858515
21	289947745327853737

[1, 5, 27, 175, 1165, 8221, 60007, 449693, 3437315, 26700429, 210147859, 1672294243, 13432357463, 108761156653, 886785526897, 7274670122017, 59999774031797, 497244626964801, 4138638973241695, 34580160863858515, 289947745327853737]

cp's OEIS Frontend

A225309 Number of nX8 -1,1 arrays such that the sum over i=1..n,j=1..8 of i*x(i,j) is zero and rows are nondecreasing (ways to put 8 thrusters pointing east or west at each of n positions 1..n distance from the hinge of a south-pointing gate without turning the gate).

Table of values

List of values