A260727 - cp's OEIS frontend

A260727 Number of ways to place 3n rooks on an n X n board, with 3 rooks in each row and each column, multiple rooks in a cell allowed, and exactly 3 rooks below the main diagonal.

n	a(n)
2	1
3	23
4	325
5	3368
6	28819
7	218788
8	1539399
9	10314315
10	66953292
11	425761614
12	2671506918
13	16618186770
14	102796975770
15	633596982417
16	3896224129259
17	23924104985984
18	146764696175937
19	899809941054468
20	5514653407814317
21	33789681789605283
22	207007665004469906

[1, 23, 325, 3368, 28819, 218788, 1539399, 10314315, 66953292, 425761614, 2671506918, 16618186770, 102796975770, 633596982417, 3896224129259, 23924104985984, 146764696175937, 899809941054468, 5514653407814317, 33789681789605283, 207007665004469906]

cp's OEIS Frontend

A260727 Number of ways to place 3n rooks on an n X n board, with 3 rooks in each row and each column, multiple rooks in a cell allowed, and exactly 3 rooks below the main diagonal.

Table of values

List of values