A247291-OEIS公司

247291元作为一个简单的表

n个	a（n）
0	1
1	1
2	2
三	4
4	7
5	15
6	32
7	69
8	154
9	346
10	786
11	1806
12	4180
13	9745
14	22865
15	53938
16	127865
17	304447
18	727733
19	1745736
20	4201350
21	10140975
22	24544000
23	59551327
24	144822097
25	352940719
26	861839226
27	2108381480
28	5166749329
29	12681855551
30	31174671514
31	76742344774

[1,1,2,4,7,15,32,69,154,346,786,1806,4180,9745,22865,53938,127865,304447,727733,1745736,4201350,10140975,24544000,59551327,144822097,352940719,861839226,2108381480,5166749329,12681855551,31174671514,76742344774]