A217617 - cp's OEIS frontend

A217617 G.f.: Sum_{n>=0} x^n * Sum_{k=0..n} binomial(n,k)^2 * x^k*(3-x)^(n-k).

n	a(n)
0	1
1	3
2	9
3	33
4	133
5	549
6	2295
7	9711
8	41505
9	178749
10	774387
11	3370995
12	14733043
13	64608555
14	284143257
15	1252749777
16	5535201733
17	24503713893
18	108659076723
19	482566381299
20	2146042722591
21	9555487997247
22	42594294578949
23	190060286569677
24	848858809506279
25	3794468370955587

[1, 3, 9, 33, 133, 549, 2295, 9711, 41505, 178749, 774387, 3370995, 14733043, 64608555, 284143257, 1252749777, 5535201733, 24503713893, 108659076723, 482566381299, 2146042722591, 9555487997247, 42594294578949, 190060286569677, 848858809506279, 3794468370955587]

cp's OEIS Frontend

A217617 G.f.: Sum_{n>=0} x^n * Sum_{k=0..n} binomial(n,k)^2 * x^k*(3-x)^(n-k).

Table of values

List of values