The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 14 |
| 3 | 66 |
| 4 | 306 |
| 5 | 1489 |
| 6 | 7106 |
| 7 | 34021 |
| 8 | 162800 |
| 9 | 779173 |
| 10 | 3731019 |
| 11 | 17861710 |
| 12 | 85505996 |
| 13 | 409326530 |
| 14 | 1959518173 |
| 15 | 9380666694 |
| 16 | 44907278950 |
| 17 | 214980183814 |
| 18 | 1029152921923 |
| 19 | 4926762747428 |
| 20 | 23585417675523 |
| 21 | 112908198853318 |
| 22 | 540514482104282 |
[2,14,66,306,1489,7106,34021,162800,779173, 3731019,17861710,85505996,409326530,1959518173, 9380666694,44907278950,214980183814,1029152921923, 4926762747428,23585417675523,112908198853318, 540514482104282] |