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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 13 |
| 4 | 98 |
| 5 | 1026 |
| 6 | 16940 |
| 7 | 318402 |
| 8 | 8751951 |
| 9 | 138772480 |
| 10 | 4323245864 |
| 11 | 120795955200 |
| 12 | 5325759445800 |
| 13 | 253615827548160 |
| 14 | 17175333492928512 |
| 15 | 1074413211620474880 |
| 16 | 76931332113306746880 |
| 17 | 5820049307236627906560 |
| 18 | 433263727052606574415872 |
[1,3,13,98,1026,16940,318402,8751951,138772480, 4323245864,120795955200,5325759445800, 253615827548160,17175333492928512, 1074413211620474880,76931332113306746880, 5820049307236627906560,433263727052606574415872] |