n | a(n) |
---|---|
0 | 1 |
1 | 1 |
2 | 4 |
3 | 15 |
4 | 76 |
5 | 368 |
6 | 2365 |
7 | 14892 |
8 | 116236 |
9 | 966064 |
10 | 9256889 |
11 | 96638496 |
12 | 1129309316 |
13 | 14261533248 |
14 | 196315312964 |
15 | 2900635720869 |
16 | 45926240752560 |
17 | 773725147192412 |
18 | 13831256551416480 |
19 | 261227089570409028 |
20 | 5198858467673903360 |
21 | 108706624576630569271 |
[1,1,4,15,76,368,2365,14892,116236,966064,9256889, 96638496,1129309316,14261533248,196315312964, 2900635720869,45926240752560,773725147192412, 13831256551416480,261227089570409028, 5198858467673903360,108706624576630569271] |