A215287 - cp's OEIS frontend

A215287 Number of permutations of 0..floor((n*3-1)/2) on even squares of an n X 3 array such that each row and column of even squares is increasing.

n	a(n)
1	1
2	3
3	10
4	30
5	140
6	420
7	2310
8	6930
9	42042
10	126126
11	816816
12	2450448
13	16628040
14	49884120
15	350574510
16	1051723530
17	7595781050
18	22787343150
19	168212023980
20	504636071940
21	3792416540640
22	11377249621920
23	86787993910800
24	260363981732400
25	2011383287449200

[1, 3, 10, 30, 140, 420, 2310, 6930, 42042, 126126, 816816, 2450448, 16628040, 49884120, 350574510, 1051723530, 7595781050, 22787343150, 168212023980, 504636071940, 3792416540640, 11377249621920, 86787993910800, 260363981732400, 2011383287449200]

cp's OEIS Frontend

A215287 Number of permutations of 0..floor((n*3-1)/2) on even squares of an n X 3 array such that each row and column of even squares is increasing.

Table of values

List of values