The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 6 |
| 4 | 13 |
| 5 | 39 |
| 6 | 131 |
| 7 | 448 |
| 8 | 1547 |
| 9 | 5352 |
| 10 | 18524 |
| 11 | 64125 |
| 12 | 221990 |
| 13 | 768506 |
| 14 | 2660499 |
| 15 | 9210416 |
| 16 | 31885663 |
| 17 | 110385418 |
| 18 | 382144818 |
| 19 | 1322952481 |
[1,3,6,13,39,131,448,1547,5352,18524,64125,221990, 768506,2660499,9210416,31885663,110385418, 382144818,1322952481] |