The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 8 |
| 5 | 20 |
| 6 | 52 |
| 7 | 146 |
| 8 | 458 |
| 9 | 1498 |
| 10 | 5240 |
| 11 | 19562 |
| 12 | 76006 |
| 13 | 311258 |
| 14 | 1334108 |
| 15 | 5931250 |
| 16 | 27492122 |
| 17 | 132096626 |
| 18 | 655783888 |
| 19 | 3368747018 |
| 20 | 17837850110 |
| 21 | 97228103482 |
| 22 | 545514383396 |
| 23 | 3142793126018 |
| 24 | 18578114240578 |
| 25 | 112620106745570 |
| 26 | 698987455899992 |
| 27 | 4439420959115866 |
| 28 | 28832596784976998 |
| 29 | 191284437539842538 |
[1,1,2,4,8,20,52,146,458,1498,5240,19562,76006, 311258,1334108,5931250,27492122,132096626, 655783888,3368747018,17837850110,97228103482, 545514383396,3142793126018,18578114240578, 112620106745570,698987455899992,4439420959115866, 28832596784976998,191284437539842538] |