A221371 - cp's OEIS frontend

A221371 O.g.f.: Sum_{n>=0} n!^2 * x^n * Product_{k=1..n} (1 + x) / (1 + k^2x + k^2x^2).

n	a(n)
0	1
1	1
2	4
3	23
4	209
5	2744
6	49539
7	1180281
8	35921892
9	1360513711
10	62770245601
11	3466178083312
12	225719029475675
13	17117740162448105
14	1495526385479298140
15	149120758170390404103
16	16831018302445533666705
17	2134813624482300873515304
18	302332062412598445891728563

[1, 1, 4, 23, 209, 2744, 49539, 1180281, 35921892, 1360513711, 62770245601, 3466178083312, 225719029475675, 17117740162448105, 1495526385479298140, 149120758170390404103, 16831018302445533666705, 2134813624482300873515304, 302332062412598445891728563]

cp's OEIS Frontend

A221371 O.g.f.: Sum_{n>=0} n!^2 * x^n * Product_{k=1..n} (1 + x) / (1 + k^2x + k^2x^2).

Table of values

List of values

cp's OEIS Frontend

A221371 O.g.f.: Sum_{n>=0} n!^2 * x^n * Product_{k=1..n} (1 + x) / (1 + k^2*x + k^2*x^2).

Table of values

List of values

A221371 O.g.f.: Sum_{n>=0} n!^2 * x^n * Product_{k=1..n} (1 + x) / (1 + k^2x + k^2x^2).