A109742 - cp's OEIS frontend

A109742 a(n) = d(n-1) + d(n-2) + (n-1)[d(n-2) + 2d(n-3) + d(n-4)], where d(n), the derangement numbers, are given in A000166. (Let d(n) = 0 if n < 0.)

n	a(n)
1	1
2	2
3	5
4	9
5	27
6	123
7	693
8	4653
9	36111
10	317583
11	3118617
12	33804177
13	400755267
14	5156954019
15	71572594557
16	1065571143093
17	16938122939703
18	286298719063863
19	5127206924693601
20	96975312507734553
21	1931609062232400747
22	40414621201681598667
23	886153986344092389957

[1, 2, 5, 9, 27, 123, 693, 4653, 36111, 317583, 3118617, 33804177, 400755267, 5156954019, 71572594557, 1065571143093, 16938122939703, 286298719063863, 5127206924693601, 96975312507734553, 1931609062232400747, 40414621201681598667, 886153986344092389957]

cp's OEIS Frontend

A109742 a(n) = d(n-1) + d(n-2) + (n-1)[d(n-2) + 2d(n-3) + d(n-4)], where d(n), the derangement numbers, are given in A000166. (Let d(n) = 0 if n < 0.)

Table of values

List of values