The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 6 |
| 3 | 20 |
| 4 | 99 |
| 5 | 441 |
| 6 | 2193 |
| 7 | 10795 |
| 8 | 55233 |
| 9 | 284735 |
| 10 | 1494404 |
| 11 | 7914270 |
| 12 | 42360541 |
| 13 | 228460935 |
| 14 | 1241224182 |
| 15 | 6784445340 |
| 16 | 37288826697 |
| 17 | 205937705799 |
| 18 | 1142317727466 |
| 19 | 6361104740100 |
| 20 | 35548154733969 |
| 21 | 199295884785459 |
| 22 | 1120615326442269 |
| 23 | 6318077793648075 |
| 24 | 35710056983891367 |
| 25 | 202297486497822121 |
[1,1,6,20,99,441,2193,10795,55233,284735,1494404, 7914270,42360541,228460935,1241224182,6784445340, 37288826697,205937705799,1142317727466, 6361104740100,35548154733969,199295884785459, 1120615326442269,6318077793648075, 35710056983891367,202297486497822121] |