The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 11 |
| 4 | 36 |
| 5 | 125 |
| 6 | 451 |
| 7 | 1611 |
| 8 | 6098 |
| 9 | 23153 |
| 10 | 88821 |
| 11 | 346225 |
| 12 | 1365886 |
| 13 | 5401489 |
| 14 | 21606970 |
| 15 | 86968247 |
| 16 | 351607286 |
| 17 | 1428888059 |
| 18 | 5840997903 |
| 19 | 23943014939 |
| 20 | 98559682258 |
| 21 | 407172518273 |
| 22 | 1687183992996 |
| 23 | 7009130833603 |
| 24 | 29208987996046 |
| 25 | 121986919568951 |
| 26 | 510636734720537 |
| 27 | 2142104892732337 |
| 28 | 9004523704570678 |
[1,1,4,11,36,125,451,1611,6098,23153,88821,346225, 1365886,5401489,21606970,86968247,351607286, 1428888059,5840997903,23943014939,98559682258, 407172518273,1687183992996,7009130833603, 29208987996046,121986919568951,510636734720537, 2142104892732337,9004523704570678] |