A015502 - cp's OEIS frontend

A015502 a(1) = 1, a(n) = Sum_{k=1..n-1} (3^k - 1)/2 * a(k).

n	a(n)
1	1
2	1
3	5
4	70
5	2870
6	350140
7	127801100
8	139814403400
9	458731057555400
10	4514831068460246800
11	133300387296288786770000
12	11806948504381482999365980000
13	3137354163532752044074527571580000
14	2500979519710095684958538548015855960000

[1, 1, 5, 70, 2870, 350140, 127801100, 139814403400, 458731057555400, 4514831068460246800, 133300387296288786770000, 11806948504381482999365980000, 3137354163532752044074527571580000, 2500979519710095684958538548015855960000]

cp's OEIS Frontend

A015502 a(1) = 1, a(n) = Sum_{k=1..n-1} (3^k - 1)/2 * a(k).

Table of values

List of values