n | a(n) |
---|---|
2 | 1 |
3 | 9 |
4 | 40 |
5 | 240 |
6 | 915 |
7 | 5103 |
8 | 18704 |
9 | 101952 |
10 | 368490 |
11 | 1990890 |
12 | 7154928 |
13 | 38514528 |
14 | 138086403 |
15 | 742202055 |
16 | 2658662560 |
17 | 14283407616 |
18 | 51156225342 |
19 | 274842096462 |
20 | 984532674800 |
21 | 5291030979360 |
22 | 18960255044654 |
23 | 101937273452454 |
24 | 365451691152864 |
[1,9,40,240,915,5103,18704,101952,368490,1990890, 7154928,38514528,138086403,742202055,2658662560, 14283407616,51156225342,274842096462,984532674800, 5291030979360,18960255044654,101937273452454, 365451691152864] |