A179089 - cp's OEIS frontend

A179089 a(n) = (1/n^2) * Sum_{k=0..n-1} (2k+1)*T_k^2(-3)^(n-1-k), where T_0, T_1, ... are central trinomial coefficients given by A002426.

n	a(n)
1	1
2	0
3	5
4	13
5	105
6	576
7	4005
8	27000
9	193193
10	1402672
11	10433709
12	78807785
13	603996745
14	4683970032
15	36702939429
16	290184446349
17	2312460578025
18	18556825469040
19	149842592021997
20	1216719520281045
21	9929612901775761
22	81406058258856240

[1, 0, 5, 13, 105, 576, 4005, 27000, 193193, 1402672, 10433709, 78807785, 603996745, 4683970032, 36702939429, 290184446349, 2312460578025, 18556825469040, 149842592021997, 1216719520281045, 9929612901775761, 81406058258856240]

cp's OEIS Frontend

A179089 a(n) = (1/n^2) * Sum_{k=0..n-1} (2k+1)*T_k^2(-3)^(n-1-k), where T_0, T_1, ... are central trinomial coefficients given by A002426.

Table of values

List of values