The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 11 |
| 3 | 43 |
| 4 | 220 |
| 5 | 984 |
| 6 | 5110 |
| 7 | 24200 |
| 8 | 127649 |
| 9 | 626505 |
| 10 | 3345863 |
| 11 | 16847161 |
| 12 | 90863911 |
| 13 | 466507567 |
| 14 | 2536185547 |
| 15 | 13221761945 |
| 16 | 72350925134 |
| 17 | 381847149426 |
| 18 | 2100852968144 |
| 19 | 11199635371558 |
| 20 | 61899477831260 |
| 21 | 332745848952712 |
| 22 | 1846197664841460 |
| 23 | 9994041629456490 |
| 24 | 55635847260490940 |
[1,2,11,43,220,984,5110,24200,127649,626505, 3345863,16847161,90863911,466507567,2536185547, 13221761945,72350925134,381847149426, 2100852968144,11199635371558,61899477831260, 332745848952712,1846197664841460,9994041629456490, 55635847260490940] |