n | a(n) |
---|---|
0 | 1 |
1 | 1 |
2 | 4 |
3 | 21 |
4 | 124 |
5 | 705 |
6 | 3726 |
7 | 18361 |
8 | 85240 |
9 | 376641 |
10 | 1597690 |
11 | 6551721 |
12 | 26116740 |
13 | 101647585 |
14 | 387634534 |
15 | 1452554265 |
16 | 5360857456 |
17 | 19523426433 |
18 | 70272302706 |
19 | 250318462537 |
20 | 883418329660 |
21 | 3091835703201 |
22 | 10739780397214 |
[1,1,4,21,124,705,3726,18361,85240,376641,1597690, 6551721,26116740,101647585,387634534,1452554265, 5360857456,19523426433,70272302706,250318462537, 883418329660,3091835703201,10739780397214] |