A331817 - cp's OEIS frontend

A331817 a(n) = (n!)^2 * Sum_{k=0..n} (2k)! / (2^k (k!)^3 * (n - k)!).

n	a(n)
0	1
1	2
2	9
3	66
4	681
5	9090
6	148905
7	2889810
8	64805265
9	1648535490
10	46896669225
11	1475099460450
12	50831084252025
13	1904311245686850
14	77061447551313225
15	3349828945512299250
16	155672917524626126625
17	7701743926471878533250
18	404153655359180645543625

[1, 2, 9, 66, 681, 9090, 148905, 2889810, 64805265, 1648535490, 46896669225, 1475099460450, 50831084252025, 1904311245686850, 77061447551313225, 3349828945512299250, 155672917524626126625, 7701743926471878533250, 404153655359180645543625]

cp's OEIS Frontend

A331817 a(n) = (n!)^2 * Sum_{k=0..n} (2k)! / (2^k (k!)^3 * (n - k)!).

Table of values

List of values

cp's OEIS Frontend

A331817 a(n) = (n!)^2 * Sum_{k=0..n} (2*k)! / (2^k * (k!)^3 * (n - k)!).

Table of values

List of values

A331817 a(n) = (n!)^2 * Sum_{k=0..n} (2k)! / (2^k (k!)^3 * (n - k)!).