The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 7 |
| 1 | 21 |
| 2 | 69 |
| 3 | 233 |
| 4 | 793 |
| 5 | 2705 |
| 6 | 9233 |
| 7 | 31521 |
| 8 | 107617 |
| 9 | 367425 |
| 10 | 1254465 |
| 11 | 4283009 |
| 12 | 14623105 |
| 13 | 49926401 |
| 14 | 170459393 |
| 15 | 581984769 |
| 16 | 1987020289 |
| 17 | 6784111617 |
| 18 | 23162405889 |
| 19 | 79081400321 |
| 20 | 270000789505 |
| 21 | 921840357377 |
| 22 | 3147359850497 |
| 23 | 10745758687233 |
[7,21,69,233,793,2705,9233,31521,107617,367425, 1254465,4283009,14623105,49926401,170459393, 581984769,1987020289,6784111617,23162405889, 79081400321,270000789505,921840357377, 3147359850497,10745758687233] |