A231274 - cp's OEIS frontend

A231274 G.f.: Sum_{n>=0} x^n * Product_{k=1..n} (k + x) / (1 - k*x - x^2).

n	a(n)
0	1
1	1
2	4
3	18
4	104
5	736
6	6232
7	61632
8	698144
9	8917120
10	126807520
11	1987075872
12	34018221728
13	631698903712
14	12645901972000
15	271482140140704
16	6221487421328672
17	151587364647728032
18	3912949321334320672
19	106670353381399285920
20	3062317963564624162592
21	92345208262957730327968

[1, 1, 4, 18, 104, 736, 6232, 61632, 698144, 8917120, 126807520, 1987075872, 34018221728, 631698903712, 12645901972000, 271482140140704, 6221487421328672, 151587364647728032, 3912949321334320672, 106670353381399285920, 3062317963564624162592, 92345208262957730327968]

cp's OEIS Frontend

A231274 G.f.: Sum_{n>=0} x^n * Product_{k=1..n} (k + x) / (1 - k*x - x^2).

Table of values

List of values