A005220-OEIS公司

A005220型作为一个简单的表

n个	a（n）
0	1
1	0
2	1
三	0
4	三
5	2
6	12
7	14
8	54
9	86
10	274
11	528
12	1515
13	3266
14	8854
15	20422
16	53786
17	129368
18	336103
19	830148
20	2145020
21	5390580
22	13913325
23	35378586
24	91415954
25	234397542
26	606983495
27	1566013450
28	4065765499
29	10540066710
30	27437831060
31	71404804002

[1,0,1,0,3,2,12,14,54,86,274,528,1515,3266,8854,20422,53786,129368,336103,830148,2145020,5390580,13913325,35378586,91415954,234397542,606983495,1566013450,4065765499,10540066710,27437831060,71404804002]