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 | 453 |
| 7 | 1615 |
| 8 | 6132 |
| 9 | 23315 |
| 10 | 89109 |
| 11 | 348805 |
| 12 | 1375922 |
| 13 | 5429329 |
| 14 | 21765534 |
| 15 | 87663419 |
| 16 | 353523880 |
| 17 | 1439753549 |
| 18 | 5886395981 |
| 19 | 24090905151 |
| 20 | 99280297840 |
| 21 | 410368064685 |
| 22 | 1697958823134 |
| 23 | 7060899122921 |
| 24 | 29433783295882 |
| 25 | 122811558530157 |
| 26 | 514382368379719 |
| 27 | 2158703728224241 |
| 28 | 9067292750103322 |
[1,1,4,11,36,125,453,1615,6132,23315,89109,348805, 1375922,5429329,21765534,87663419,353523880, 1439753549,5886395981,24090905151,99280297840, 410368064685,1697958823134,7060899122921, 29433783295882,122811558530157,514382368379719, 2158703728224241,9067292750103322] |