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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 6 |
| 2 | 31 |
| 3 | 158 |
| 4 | 975 |
| 5 | 6639 |
| 6 | 48050 |
| 7 | 362592 |
| 8 | 2820789 |
| 9 | 22460120 |
| 10 | 182141553 |
| 11 | 1499143282 |
| 12 | 12490923757 |
| 13 | 105150960654 |
| 14 | 892973346300 |
| 15 | 7640934031920 |
| 16 | 65813450140017 |
| 17 | 570160918044288 |
| 18 | 4964875184429660 |
| 19 | 43431741548248440 |
| 20 | 381496856026500220 |
| 21 | 3363457643008999635 |
[0,6,31,158,975,6639,48050,362592,2820789, 22460120,182141553,1499143282,12490923757, 105150960654,892973346300,7640934031920, 65813450140017,570160918044288,4964875184429660, 43431741548248440,381496856026500220, 3363457643008999635] |