A357442 - cp's OEIS frontend

A357442 Consider a clock face with 2*n "hours" marked around the dial; a(n) = number of ways to match the even hours to the odd hours, modulo rotations and reflections.

n	a(n)
1	1
2	1
3	3
4	5
5	17
6	53
7	260
8	1466
9	10915
10	93196
11	917898
12	10015299
13	119914982
14	1557364352
15	21797494987
16	326930305166
17	5230756117008
18	88922108947567
19	1600594738591550
20	30411281088326498
21	608225534389576956
22	12772735698577492558

[1, 1, 3, 5, 17, 53, 260, 1466, 10915, 93196, 917898, 10015299, 119914982, 1557364352, 21797494987, 326930305166, 5230756117008, 88922108947567, 1600594738591550, 30411281088326498, 608225534389576956, 12772735698577492558]

cp's OEIS Frontend

A357442 Consider a clock face with 2*n "hours" marked around the dial; a(n) = number of ways to match the even hours to the odd hours, modulo rotations and reflections.

Table of values

List of values