A103211 - cp's OEIS frontend

A103211 a(n) = (1/n) * Sum_{i=0..n-1} C(n,i)C(n,i+1)3^i*4^(n-i), a(0)=1.

n	a(n)
0	1
1	4
2	28
3	244
4	2380
5	24868
6	272188
7	3080596
8	35758828
9	423373636
10	5092965724
11	62071299892
12	764811509644
13	9511373563492
14	119231457692284
15	1505021128450516
16	19112961439180588
17	244028820862442116
18	3130592301487969948
19	40333745806536135028
20	521655330655122923980

[1, 4, 28, 244, 2380, 24868, 272188, 3080596, 35758828, 423373636, 5092965724, 62071299892, 764811509644, 9511373563492, 119231457692284, 1505021128450516, 19112961439180588, 244028820862442116, 3130592301487969948, 40333745806536135028, 521655330655122923980]

cp's OEIS Frontend

A103211 a(n) = (1/n) * Sum_{i=0..n-1} C(n,i)C(n,i+1)3^i*4^(n-i), a(0)=1.

Table of values

List of values

cp's OEIS Frontend

A103211 a(n) = (1/n) * Sum_{i=0..n-1} C(n,i)*C(n,i+1)*3^i*4^(n-i), a(0)=1.

Table of values

List of values

A103211 a(n) = (1/n) * Sum_{i=0..n-1} C(n,i)C(n,i+1)3^i*4^(n-i), a(0)=1.