The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 7 |
| 3 | 33 |
| 4 | 146 |
| 5 | 664 |
| 6 | 3199 |
| 7 | 16479 |
| 8 | 90774 |
| 9 | 532870 |
| 10 | 3319142 |
| 11 | 21844498 |
| 12 | 151329352 |
| 13 | 1099821989 |
| 14 | 8361242674 |
| 15 | 66320784806 |
| 16 | 547602705993 |
| 17 | 4697109617699 |
| 18 | 41777867535655 |
| 19 | 384671271441332 |
| 20 | 3661037447438874 |
| 21 | 35965775221693131 |
[1,7,33,146,664,3199,16479,90774,532870,3319142, 21844498,151329352,1099821989,8361242674, 66320784806,547602705993,4697109617699, 41777867535655,384671271441332,3661037447438874, 35965775221693131] |