| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 6 |
| 5 | 22 |
| 6 | 92 |
| 7 | 508 |
| 8 | 3674 |
| 9 | 34452 |
| 10 | 408104 |
| 11 | 5925564 |
| 12 | 103023888 |
| 13 | 2102941162 |
| 14 | 49588317960 |
| 15 | 1332831700026 |
| 16 | 40376512041704 |
| 17 | 1365483356241318 |
| 18 | 51130344360226830 |
| 19 | 2104788801045148866 |
| 20 | 94659739599219674872 |
| 21 | 4625501078986781603540 |
| 22 | 244380566194237434434094 |
[1,1,2,6,22,92,508,3674,34452,408104,5925564, 103023888,2102941162,49588317960,1332831700026, 40376512041704,1365483356241318,51130344360226830, 2104788801045148866,94659739599219674872, 4625501078986781603540,244380566194237434434094] |