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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 7 |
| 4 | 40 |
| 5 | 338 |
| 6 | 3841 |
| 7 | 54821 |
| 8 | 939335 |
| 9 | 18744832 |
| 10 | 426390069 |
| 11 | 10881017916 |
| 12 | 307686450208 |
| 13 | 9546443638409 |
| 14 | 322375619648549 |
| 15 | 11769010007246745 |
| 16 | 461834905502223078 |
| 17 | 19384809864763869231 |
| 18 | 866564718107731746860 |
| 19 | 41102477939620052536314 |
[1,1,2,7,40,338,3841,54821,939335,18744832, 426390069,10881017916,307686450208,9546443638409, 322375619648549,11769010007246745, 461834905502223078,19384809864763869231, 866564718107731746860,41102477939620052536314] |