A137730 - cp's OEIS frontend

A137730 Number of circular permutations of the multiset {1,1,2,2,...,n,n} (up to rotations) with odd distances between equal elements.

n	a(n)
1	1
2	1
3	7
4	72
5	1452
6	43200
7	1814760
8	101606400
9	7315680960
10	658409472000
11	72425043734400
12	9560105533440000
13	1491376463456140800
14	271430516305428480000
15	57000408424183569945600
16	13680098021793595392000000
17	3720986661927868408018944000
18	1138621918549924531666944000000

[1, 1, 7, 72, 1452, 43200, 1814760, 101606400, 7315680960, 658409472000, 72425043734400, 9560105533440000, 1491376463456140800, 271430516305428480000, 57000408424183569945600, 13680098021793595392000000, 3720986661927868408018944000, 1138621918549924531666944000000]

cp's OEIS Frontend

A137730 Number of circular permutations of the multiset {1,1,2,2,...,n,n} (up to rotations) with odd distances between equal elements.

Table of values

List of values