The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 8 |
| 4 | 36 |
| 5 | 100 |
| 6 | 458 |
| 7 | 1462 |
| 8 | 6809 |
| 9 | 23521 |
| 10 | 111180 |
| 11 | 405288 |
| 12 | 1935161 |
| 13 | 7330542 |
| 14 | 35252989 |
| 15 | 137422833 |
| 16 | 664576216 |
| 17 | 2649175259 |
| 18 | 12867856516 |
| 19 | 52224563411 |
| 20 | 254550418677 |
| 21 | 1048465569279 |
| 22 | 5124668686800 |
| 23 | 21370196670463 |
| 24 | 104693461764880 |
| 25 | 441179953011886 |
| 26 | 2165508882775008 |
| 27 | 9208165544591383 |
| 28 | 45270898259206533 |
[1,1,4,8,36,100,458,1462,6809,23521,111180,405288, 1935161,7330542,35252989,137422833,664576216, 2649175259,12867856516,52224563411,254550418677, 1048465569279,5124668686800,21370196670463, 104693461764880,441179953011886,2165508882775008, 9208165544591383,45270898259206533] |