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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 4 |
| 3 | 15 |
| 4 | 64 |
| 5 | 317 |
| 6 | 1728 |
| 7 | 10268 |
| 8 | 65536 |
| 9 | 445376 |
| 10 | 3200000 |
| 11 | 24172677 |
| 12 | 191102976 |
| 13 | 1575167570 |
| 14 | 13492928512 |
| 15 | 119786923327 |
| 16 | 1099511627776 |
| 17 | 10412878353557 |
| 18 | 101559956668416 |
| 19 | 1018460448140641 |
| 20 | 10485760000000000 |
| 21 | 110692335104026964 |
| 22 | 1196683881290399744 |
[1,2,4,15,64,317,1728,10268,65536,445376,3200000, 24172677,191102976,1575167570,13492928512, 119786923327,1099511627776,10412878353557, 101559956668416,1018460448140641, 10485760000000000,110692335104026964, 1196683881290399744] |