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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 34 |
| 3 | 337 |
| 4 | 3554 |
| 5 | 38754 |
| 6 | 431521 |
| 7 | 4874377 |
| 8 | 55639010 |
| 9 | 640177033 |
| 10 | 7412165034 |
| 11 | 86256322816 |
| 12 | 1007980394849 |
| 13 | 11820510331777 |
| 14 | 139032549536551 |
| 15 | 1639506780365337 |
| 16 | 19376785465043938 |
| 17 | 229458302589724067 |
| 18 | 2721958273545613513 |
| 19 | 32339465512495259708 |
| 20 | 384758834631081248554 |
[1,4,34,337,3554,38754,431521,4874377,55639010, 640177033,7412165034,86256322816,1007980394849, 11820510331777,139032549536551,1639506780365337, 19376785465043938,229458302589724067, 2721958273545613513,32339465512495259708, 384758834631081248554] |