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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 511 |
| 3 | 19682 |
| 4 | 262143 |
| 5 | 1953124 |
| 6 | 10077695 |
| 7 | 40353606 |
| 8 | 134217727 |
| 9 | 387420488 |
| 10 | 999999999 |
| 11 | 2357947690 |
| 12 | 5159780351 |
| 13 | 10604499372 |
| 14 | 20661046783 |
| 15 | 38443359374 |
| 16 | 68719476735 |
| 17 | 118587876496 |
| 18 | 198359290367 |
| 19 | 322687697778 |
| 20 | 511999999999 |
| 21 | 794280046580 |
| 22 | 1207269217791 |
| 23 | 1801152661462 |
[0,511,19682,262143,1953124,10077695,40353606, 134217727,387420488,999999999,2357947690, 5159780351,10604499372,20661046783,38443359374, 68719476735,118587876496,198359290367, 322687697778,511999999999,794280046580, 1207269217791,1801152661462] |