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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 5 |
| 2 | 60 |
| 3 | 1001 |
| 4 | 19380 |
| 5 | 408595 |
| 6 | 9104550 |
| 7 | 210905400 |
| 8 | 5028168132 |
| 9 | 122563178210 |
| 10 | 3040594338320 |
| 11 | 76520801509425 |
| 12 | 1948777701739050 |
| 13 | 50129821093933224 |
| 14 | 1300611345665798320 |
| 15 | 33994757853301868560 |
| 16 | 894295618431497324900 |
| 17 | 23660280955151412585930 |
| 18 | 629143806228348421209768 |
[1,5,60,1001,19380,408595,9104550,210905400, 5028168132,122563178210,3040594338320, 76520801509425,1948777701739050,50129821093933224, 1300611345665798320,33994757853301868560, 894295618431497324900,23660280955151412585930, 629143806228348421209768] |