A001205 - cp's OEIS frontend

A001205 Number of clouds with n points; number of undirected 2-regular labeled graphs; or number of n X n symmetric matrices with (0,1) entries, trace 0 and all row sums 2.

n	a(n)
0	1
1	0
2	0
3	1
4	3
5	12
6	70
7	465
8	3507
9	30016
10	286884
11	3026655
12	34944085
13	438263364
14	5933502822
15	86248951243
16	1339751921865
17	22148051088480
18	388246725873208
19	7193423109763089
20	140462355821628771
21	2883013994348484940

[1, 0, 0, 1, 3, 12, 70, 465, 3507, 30016, 286884, 3026655, 34944085, 438263364, 5933502822, 86248951243, 1339751921865, 22148051088480, 388246725873208, 7193423109763089, 140462355821628771, 2883013994348484940]

cp's OEIS Frontend

A001205 Number of clouds with n points; number of undirected 2-regular labeled graphs; or number of n X n symmetric matrices with (0,1) entries, trace 0 and all row sums 2.

Table of values

List of values