The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 2 |
| 3 | 3 |
| 4 | 13 |
| 5 | 32 |
| 6 | 121 |
| 7 | 376 |
| 8 | 1406 |
| 9 | 5030 |
| 10 | 19632 |
| 11 | 76334 |
| 12 | 314582 |
| 13 | 1308550 |
| 14 | 5667494 |
| 15 | 24940458 |
| 16 | 113239394 |
| 17 | 523149560 |
| 18 | 2480434938 |
| 19 | 11968944532 |
| 20 | 59051754824 |
[1,0,2,3,13,32,121,376,1406,5030,19632,76334, 314582,1308550,5667494,24940458,113239394, 523149560,2480434938,11968944532,59051754824] |