A055217 - cp's OEIS frontend

A055217 a(n) = sum of the first n coefficients of (1+x+x^2)^n.

n	a(n)
0	1
1	3
2	10
3	31
4	96
5	294
6	897
7	2727
8	8272
9	25048
10	75747
11	228826
12	690691
13	2083371
14	6280650
15	18925047
16	57002616
17	171633840
18	516632307
19	1554702516
20	4677501237
21	14069962041
22	42314975352
23	127240600050
24	382555886571
25	1150026301089

[1, 3, 10, 31, 96, 294, 897, 2727, 8272, 25048, 75747, 228826, 690691, 2083371, 6280650, 18925047, 57002616, 171633840, 516632307, 1554702516, 4677501237, 14069962041, 42314975352, 127240600050, 382555886571, 1150026301089]

cp's OEIS Frontend

A055217 a(n) = sum of the first n coefficients of (1+x+x^2)^n.

Table of values

List of values