The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 2 | 21 |
| 3 | 110 |
| 4 | 581 |
| 5 | 3070 |
| 6 | 16227 |
| 7 | 85776 |
| 8 | 453423 |
| 9 | 2396868 |
| 10 | 12670261 |
| 11 | 66977242 |
| 12 | 354053617 |
| 13 | 1871590506 |
| 14 | 9893561055 |
| 15 | 52299127660 |
| 16 | 276462513603 |
| 17 | 1461430140016 |
| 18 | 7725380293233 |
| 19 | 40837737667414 |
| 20 | 215875562691877 |
[21,110,581,3070,16227,85776,453423,2396868, 12670261,66977242,354053617,1871590506,9893561055, 52299127660,276462513603,1461430140016, 7725380293233,40837737667414,215875562691877] |