The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 9 |
| 3 | 57 |
| 4 | 307 |
| 5 | 1517 |
| 6 | 7103 |
| 7 | 32117 |
| 8 | 141711 |
| 9 | 614429 |
| 10 | 2629495 |
| 11 | 11141893 |
| 12 | 46846671 |
| 13 | 195760429 |
| 14 | 813970695 |
| 15 | 3370693013 |
| 16 | 13910890431 |
| 17 | 57246635581 |
| 18 | 235011903671 |
| 19 | 962772769829 |
| 20 | 3937069121647 |
| 21 | 16074491903309 |
| 22 | 65538899349479 |
| 23 | 266887332403125 |
| 24 | 1085630844057375 |
| 25 | 4411756408116573 |
| 26 | 17912600251244567 |
| 27 | 72670852531322949 |
| 28 | 294610539143446735 |
[0,1,9,57,307,1517,7103,32117,141711,614429, 2629495,11141893,46846671,195760429,813970695, 3370693013,13910890431,57246635581,235011903671, 962772769829,3937069121647,16074491903309, 65538899349479,266887332403125,1085630844057375, 4411756408116573,17912600251244567, 72670852531322949,294610539143446735] |