A368597 - cp's OEIS frontend

A368597 Number of n-element sets of singletons or pairs of distinct elements of {1..n} with union {1..n}, or loop-graphs covering n vertices with n edges.

n	a(n)
0	1
1	1
2	3
3	17
4	150
5	1803
6	27364
7	501015
8	10736010
9	263461265
10	7283725704
11	223967628066
12	7581128184175
13	280103206674480
14	11216492736563655
15	483875783716549277
16	22371631078155742764
17	1103548801569848115255
18	57849356643299101021960
19	3211439288584038922502820

[1, 1, 3, 17, 150, 1803, 27364, 501015, 10736010, 263461265, 7283725704, 223967628066, 7581128184175, 280103206674480, 11216492736563655, 483875783716549277, 22371631078155742764, 1103548801569848115255, 57849356643299101021960, 3211439288584038922502820]

cp's OEIS Frontend

A368597 Number of n-element sets of singletons or pairs of distinct elements of {1..n} with union {1..n}, or loop-graphs covering n vertices with n edges.

Table of values

List of values