The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 7 |
| 3 | 18 |
| 4 | 46 |
| 5 | 116 |
| 6 | 294 |
| 7 | 746 |
| 8 | 1894 |
| 9 | 4816 |
| 10 | 12262 |
| 11 | 31258 |
| 12 | 79777 |
| 13 | 203833 |
| 14 | 521337 |
| 15 | 1334690 |
| 16 | 3420039 |
| 17 | 8770891 |
| 18 | 22510949 |
| 19 | 57817420 |
| 20 | 148599626 |
| 21 | 382165858 |
| 22 | 983430962 |
| 23 | 2532082308 |
| 24 | 6522876601 |
| 25 | 16811813391 |
| 26 | 43350264107 |
| 27 | 111830286218 |
[1,3,7,18,46,116,294,746,1894,4816,12262,31258, 79777,203833,521337,1334690,3420039,8770891, 22510949,57817420,148599626,382165858,983430962, 2532082308,6522876601,16811813391,43350264107, 111830286218] |