A337556 - cp's OEIS frontend

A337556 a(0) = 1; a(n) = (1/3) * Sum_{k=1..n} binomial(n,k) * (4^k-1) * a(n-k).

n	a(n)
0	1
1	1
2	7
3	57
4	607
5	8121
6	130527
7	2447257
8	52435327
9	1263925881
10	33851510047
11	997303255257
12	32052722909247
13	1116001351341241
14	41845542004844767
15	1681112968022124057
16	72039936723424794367
17	3280036569708658302201
18	158127582939120607830687
19	8046697501049910668173657

[1, 1, 7, 57, 607, 8121, 130527, 2447257, 52435327, 1263925881, 33851510047, 997303255257, 32052722909247, 1116001351341241, 41845542004844767, 1681112968022124057, 72039936723424794367, 3280036569708658302201, 158127582939120607830687, 8046697501049910668173657]

cp's OEIS Frontend

A337556 a(0) = 1; a(n) = (1/3) * Sum_{k=1..n} binomial(n,k) * (4^k-1) * a(n-k).

Table of values

List of values