The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 3 | 0 |
| 4 | 0 |
| 5 | 1 |
| 6 | 353 |
| 7 | 12231 |
| 8 | 153194 |
| 9 | 1124820 |
| 10 | 5893221 |
| 11 | 24425212 |
| 12 | 85152341 |
| 13 | 259805430 |
| 14 | 712840480 |
| 15 | 1793423456 |
| 16 | 4197531636 |
| 17 | 9240962666 |
| 18 | 19301854131 |
| 19 | 38514786780 |
| 20 | 73828909906 |
| 21 | 136581190475 |
| 22 | 244784427831 |
| 23 | 426389859697 |
| 24 | 723857976770 |
| 25 | 1200460734396 |
| 26 | 1948846090829 |
| 27 | 3102524331336 |
[0,0,1,353,12231,153194,1124820,5893221,24425212, 85152341,259805430,712840480,1793423456, 4197531636,9240962666,19301854131,38514786780, 73828909906,136581190475,244784427831, 426389859697,723857976770,1200460734396, 1948846090829,3102524331336] |