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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 14 |
| 4 | 70 |
| 5 | 444 |
| 6 | 3108 |
| 7 | 25584 |
| 8 | 230256 |
| 9 | 2342880 |
| 10 | 25771680 |
| 11 | 312888960 |
| 12 | 4067556480 |
| 13 | 57424792320 |
| 14 | 861371884800 |
| 15 | 13869128448000 |
| 16 | 235775183616000 |
| 17 | 4264876094976000 |
| 18 | 81032645804544000 |
| 19 | 1627055289796608000 |
| 20 | 34168161085728768000 |
| 21 | 754132445894209536000 |
| 22 | 17345046255566819328000 |
[1,3,14,70,444,3108,25584,230256,2342880,25771680, 312888960,4067556480,57424792320,861371884800, 13869128448000,235775183616000,4264876094976000, 81032645804544000,1627055289796608000, 34168161085728768000,754132445894209536000, 17345046255566819328000] |