The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 10 |
| 3 | 50 |
| 4 | 315 |
| 5 | 2548 |
| 6 | 24750 |
| 7 | 283086 |
| 8 | 3718451 |
| 9 | 55226094 |
| 10 | 914920279 |
| 11 | 16730484550 |
| 12 | 334726087293 |
| 13 | 7273394028436 |
| 14 | 170582139327722 |
| 15 | 4294808423962382 |
| 16 | 115541406472101049 |
| 17 | 3307767234883377646 |
| 18 | 100406513593125459867 |
| 19 | 3221197891527369202071 |
| 20 | 108904600042780018935163 |
[1,3,10,50,315,2548,24750,283086,3718451,55226094, 914920279,16730484550,334726087293,7273394028436, 170582139327722,4294808423962382, 115541406472101049,3307767234883377646, 100406513593125459867,3221197891527369202071, 108904600042780018935163] |