A092473 - cp's OEIS frontend

A092473 a(n) = Sum_{i+j+k=n, 0<=i<=j<=k<=n} (2n)!/((i+j)! * (j+k)! * (k+i)!).

n	a(n)
0	1
1	2
2	18
3	170
4	1330
5	11382
6	117810
7	934362
8	8611746
9	82240730
10	699393838
11	6244164940
12	59910383026
13	507902083210
14	4599466921410
15	43063170064620
16	372282144948450
17	3338235118237410
18	31231394376541650
19	270058012725600000

[1, 2, 18, 170, 1330, 11382, 117810, 934362, 8611746, 82240730, 699393838, 6244164940, 59910383026, 507902083210, 4599466921410, 43063170064620, 372282144948450, 3338235118237410, 31231394376541650, 270058012725600000]

cp's OEIS Frontend

A092473 a(n) = Sum_{i+j+k=n, 0<=i<=j<=k<=n} (2n)!/((i+j)! * (j+k)! * (k+i)!).

Table of values

List of values