The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 6 |
| 2 | 33 |
| 3 | 146 |
| 4 | 588 |
| 5 | 2160 |
| 6 | 7459 |
| 7 | 24354 |
| 8 | 76071 |
| 9 | 228420 |
| 10 | 663177 |
| 11 | 1868220 |
| 12 | 5124224 |
| 13 | 13718748 |
| 14 | 35932278 |
| 15 | 92242982 |
| 16 | 232473006 |
| 17 | 575971494 |
| 18 | 1404600837 |
| 19 | 3375138816 |
| 20 | 7998932769 |
| 21 | 18712911214 |
| 22 | 43246451181 |
| 23 | 98799885342 |
| 24 | 223269183076 |
| 25 | 499357990254 |
| 26 | 1105934610042 |
[1,6,33,146,588,2160,7459,24354,76071,228420, 663177,1868220,5124224,13718748,35932278,92242982, 232473006,575971494,1404600837,3375138816, 7998932769,18712911214,43246451181,98799885342, 223269183076,499357990254,1105934610042] |