The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 9 |
| 4 | 38 |
| 5 | 111 |
| 6 | 489 |
| 7 | 1611 |
| 8 | 7292 |
| 9 | 25865 |
| 10 | 119229 |
| 11 | 444481 |
| 12 | 2075488 |
| 13 | 8019353 |
| 14 | 37805228 |
| 15 | 150069461 |
| 16 | 712667390 |
| 17 | 2889197265 |
| 18 | 13800198063 |
| 19 | 56900245013 |
| 20 | 273057703416 |
| 21 | 1141558272143 |
| 22 | 5499371173998 |
| 23 | 23258138316869 |
| 24 | 112406688710300 |
| 25 | 480068721208329 |
| 26 | 2326541496532377 |
| 27 | 10019955108804655 |
| 28 | 48673791102092756 |
[1,1,4,9,38,111,489,1611,7292,25865,119229,444481, 2075488,8019353,37805228,150069461,712667390, 2889197265,13800198063,56900245013,273057703416, 1141558272143,5499371173998,23258138316869, 112406688710300,480068721208329,2326541496532377, 10019955108804655,48673791102092756] |