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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 6 |
| 3 | 46 |
| 4 | 470 |
| 5 | 6035 |
| 6 | 93436 |
| 7 | 1695036 |
| 8 | 35277012 |
| 9 | 828707925 |
| 10 | 21693441550 |
| 11 | 626254969978 |
| 12 | 19766667410282 |
| 13 | 677231901484775 |
| 14 | 25031756512858200 |
| 15 | 992872579254244088 |
| 16 | 42066929594261568840 |
| 17 | 1896157095455962952169 |
| 18 | 90601933352843530354170 |
| 19 | 4574495282686422755339734 |
| 20 | 243359175218492577008763726 |
[0,1,6,46,470,6035,93436,1695036,35277012, 828707925,21693441550,626254969978,19766667410282, 677231901484775,25031756512858200, 992872579254244088,42066929594261568840, 1896157095455962952169,90601933352843530354170, 4574495282686422755339734, 243359175218492577008763726] |