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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 6 |
| 3 | 15 |
| 4 | 465 |
| 5 | 666 |
| 6 | 23436 |
| 7 | 93528 |
| 8 | 198765 |
| 9 | 664128 |
| 10 | 1493856 |
| 11 | 1786995 |
| 12 | 2767128 |
| 13 | 2953665 |
| 14 | 18292176 |
| 15 | 23891328 |
| 16 | 44655975 |
| 17 | 169878528 |
| 18 | 787667895 |
| 19 | 859984128 |
| 20 | 1934948736 |
| 21 | 3333238776 |
| 22 | 97844944896 |
| 23 | 237295393965 |
| 24 | 292957233975 |
| 25 | 379244291328 |
| 26 | 175847359339575 |
| 27 | 12999674534178816 |
[1,6,15,465,666,23436,93528,198765,664128,1493856, 1786995,2767128,2953665,18292176,23891328, 44655975,169878528,787667895,859984128,1934948736, 3333238776,97844944896,237295393965,292957233975, 379244291328,175847359339575,12999674534178816] |