The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 11 |
| 3 | 51 |
| 4 | 192 |
| 5 | 669 |
| 6 | 2222 |
| 7 | 7135 |
| 8 | 22374 |
| 9 | 68916 |
| 10 | 209348 |
| 11 | 628916 |
| 12 | 1872269 |
| 13 | 5531641 |
| 14 | 16238866 |
| 15 | 47410139 |
| 16 | 137758585 |
| 17 | 398617683 |
| 18 | 1149205715 |
| 19 | 3302324374 |
| 20 | 9461757569 |
| 21 | 27038402095 |
| 22 | 77082571383 |
| 23 | 219276117983 |
| 24 | 622541323482 |
| 25 | 1764242459656 |
[1,11,51,192,669,2222,7135,22374,68916,209348, 628916,1872269,5531641,16238866,47410139, 137758585,398617683,1149205715,3302324374, 9461757569,27038402095,77082571383,219276117983, 622541323482,1764242459656] |