A005717 - cp's OEIS frontend

A005717 Construct triangle in which n-th row is obtained by expanding (1 + x + x^2)^n and take the next-to-central column.

n	a(n)
1	1
2	2
3	6
4	16
5	45
6	126
7	357
8	1016
9	2907
10	8350
11	24068
12	69576
13	201643
14	585690
15	1704510
16	4969152
17	14508939
18	42422022
19	124191258
20	363985680
21	1067892399
22	3136046298
23	9217554129
24	27114249960
25	79818194925
26	235128465026
27	693085098852
28	2044217638456
29	6032675068061

[1, 2, 6, 16, 45, 126, 357, 1016, 2907, 8350, 24068, 69576, 201643, 585690, 1704510, 4969152, 14508939, 42422022, 124191258, 363985680, 1067892399, 3136046298, 9217554129, 27114249960, 79818194925, 235128465026, 693085098852, 2044217638456, 6032675068061]

cp's OEIS Frontend

A005717 Construct triangle in which n-th row is obtained by expanding (1 + x + x^2)^n and take the next-to-central column.

Table of values

List of values