The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 9 |
| 3 | 26 |
| 4 | 70 |
| 5 | 177 |
| 6 | 427 |
| 7 | 996 |
| 8 | 2268 |
| 9 | 5075 |
| 10 | 11209 |
| 11 | 24510 |
| 12 | 53170 |
| 13 | 114597 |
| 14 | 245655 |
| 15 | 524168 |
| 16 | 1113976 |
| 17 | 2359143 |
| 18 | 4980565 |
| 19 | 10485570 |
| 20 | 22019886 |
| 21 | 46137113 |
| 22 | 96468739 |
| 23 | 201326316 |
| 24 | 419430100 |
| 25 | 872414907 |
| 26 | 1811938977 |
| 27 | 3758096006 |
| 28 | 7784627818 |
[1,3,9,26,70,177,427,996,2268,5075,11209,24510, 53170,114597,245655,524168,1113976,2359143, 4980565,10485570,22019886,46137113,96468739, 201326316,419430100,872414907,1811938977, 3758096006,7784627818] |