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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 6 |
| 3 | 39 |
| 4 | 356 |
| 5 | 4055 |
| 6 | 57786 |
| 7 | 983535 |
| 8 | 19520264 |
| 9 | 441967518 |
| 10 | 11235798510 |
| 11 | 316719689506 |
| 12 | 9800860032876 |
| 13 | 330230585628437 |
| 14 | 12032866998445818 |
| 15 | 471416196117401340 |
| 16 | 19758835313514076176 |
| 17 | 882185444649249777913 |
| 18 | 41797472220815112375966 |
| 19 | 2094455101139881670407954 |
[1,1,6,39,356,4055,57786,983535,19520264, 441967518,11235798510,316719689506,9800860032876, 330230585628437,12032866998445818, 471416196117401340,19758835313514076176, 882185444649249777913,41797472220815112375966, 2094455101139881670407954] |