A209290 - cp's OEIS frontend

A209290 Number of elements whose preimage is the empty set summed over all functions f:{1,2,...,n}->{1,2,...,n}.

n	a(n)
0	0
1	0
2	2
3	24
4	324
5	5120
6	93750
7	1959552
8	46118408
9	1207959552
10	34867844010
11	1100000000000
12	37661140520652
13	1390911669927936
14	55123269399790046
15	2333521433367183360
16	105094533691406250000
17	5017514388048998039552
18	253135520137219049838162
19	13456471561751415850795008

[0, 0, 2, 24, 324, 5120, 93750, 1959552, 46118408, 1207959552, 34867844010, 1100000000000, 37661140520652, 1390911669927936, 55123269399790046, 2333521433367183360, 105094533691406250000, 5017514388048998039552, 253135520137219049838162, 13456471561751415850795008]

cp's OEIS Frontend

A209290 Number of elements whose preimage is the empty set summed over all functions f:{1,2,...,n}->{1,2,...,n}.

Table of values

List of values