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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 14 |
| 2 | 126 |
| 3 | 924 |
| 4 | 6006 |
| 5 | 36036 |
| 6 | 204204 |
| 7 | 1108536 |
| 8 | 5819814 |
| 9 | 29745716 |
| 10 | 148728580 |
| 11 | 730122120 |
| 12 | 3528923580 |
| 13 | 16830250920 |
| 14 | 79342611480 |
| 15 | 370265520240 |
| 16 | 1712478031110 |
| 17 | 7857252142740 |
| 18 | 35794148650260 |
[1,14,126,924,6006,36036,204204,1108536,5819814, 29745716,148728580,730122120,3528923580, 16830250920,79342611480,370265520240, 1712478031110,7857252142740,35794148650260] |