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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 26 |
| 4 | 438 |
| 5 | 11674 |
| 6 | 434613 |
| 7 | 21040885 |
| 8 | 1263748763 |
| 9 | 91057116368 |
| 10 | 7676892453542 |
| 11 | 742890018054927 |
| 12 | 81267790173334794 |
| 13 | 9926903213704358577 |
| 14 | 1340280764681712515084 |
| 15 | 198320073897808037293388 |
| 16 | 31929177807445245255119558 |
| 17 | 5558580993355817894674501169 |
| 18 | 1040777481846356463369367882750 |
[1,1,3,26,438,11674,434613,21040885,1263748763, 91057116368,7676892453542,742890018054927, 81267790173334794,9926903213704358577, 1340280764681712515084,198320073897808037293388, 31929177807445245255119558, 5558580993355817894674501169, 1040777481846356463369367882750] |