A190981-OEIS公司

A190981号作为一个简单的表

n个	a（n）
0	0
1	1
2	9
三	77
4	657
5	5605
6	47817
7	407933
8	3480129
9	29689429
10	253284345
11	2160801389
12	18434075121
13	157263470533
14	1341634934313
15	11445660526685
16	97644405002913
17	833017002919477
18	7106575406263641
19	60627110644694861
20	517217694177199185
21	4412450805016013221

[0,1,9,77,657,5605,47817,407933,3480129,29689429,253284345,2160801389,18434075121,157263470533,1341634934313,11445660526685,97644405002913,833017002919477,7106575406263641,60627110644694861,517217694177199185,4412450805016013221]