The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 4 |
| 3 | 13 |
| 4 | 34 |
| 5 | 118 |
| 6 | 419 |
| 7 | 1481 |
| 8 | 5394 |
| 9 | 19848 |
| 10 | 73880 |
| 11 | 277222 |
| 12 | 1047495 |
| 13 | 3977615 |
| 14 | 15169751 |
| 15 | 58074521 |
| 16 | 223081286 |
| 17 | 859450114 |
| 18 | 3319751314 |
| 19 | 12852496680 |
| 20 | 49860496892 |
| 21 | 193783946748 |
| 22 | 754379484650 |
| 23 | 2941051327294 |
| 24 | 11481400024511 |
| 25 | 44875877924939 |
[2,4,13,34,118,419,1481,5394,19848,73880,277222, 1047495,3977615,15169751,58074521,223081286, 859450114,3319751314,12852496680,49860496892, 193783946748,754379484650,2941051327294, 11481400024511,44875877924939] |