The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 9 |
| 3 | 33 |
| 4 | 161 |
| 5 | 680 |
| 6 | 3369 |
| 7 | 15088 |
| 8 | 75081 |
| 9 | 347064 |
| 10 | 1730781 |
| 11 | 8158649 |
| 12 | 40732877 |
| 13 | 194526790 |
| 14 | 971772573 |
| 15 | 4683554583 |
| 16 | 23404834485 |
| 17 | 113561913832 |
| 18 | 567609536625 |
| 19 | 2768123587989 |
| 20 | 13837451513575 |
| 21 | 67749630403142 |
| 22 | 338696889044933 |
| 23 | 1663493549344340 |
| 24 | 8316622638737221 |
| 25 | 40949858508495618 |
| 26 | 204735162202289217 |
[1,2,9,33,161,680,3369,15088,75081,347064,1730781, 8158649,40732877,194526790,971772573,4683554583, 23404834485,113561913832,567609536625, 2768123587989,13837451513575,67749630403142, 338696889044933,1663493549344340,8316622638737221, 40949858508495618,204735162202289217] |