The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 3 |
| 3 | 9 |
| 4 | 45 |
| 5 | 185 |
| 6 | 1277 |
| 7 | 7469 |
| 8 | 67993 |
| 9 | 514841 |
| 10 | 5414197 |
| 11 | 52609653 |
| 12 | 679432169 |
| 13 | 7704502013 |
| 14 | 111283754969 |
| 15 | 1515535050805 |
| 16 | 25257251330321 |
| 17 | 385282195339393 |
| 18 | 7088110874426409 |
| 19 | 123325149268482781 |
| 20 | 2520808658222616653 |
| 21 | 48623257343586890769 |
| 22 | 1078165538033926164281 |
[0,1,3,9,45,185,1277,7469,67993,514841,5414197, 52609653,679432169,7704502013,111283754969, 1515535050805,25257251330321,385282195339393, 7088110874426409,123325149268482781, 2520808658222616653,48623257343586890769, 1078165538033926164281] |