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| n | a(n) |
|---|---|
| 0 | 5 |
| 1 | 56 |
| 2 | 420 |
| 3 | 2640 |
| 4 | 15015 |
| 5 | 80080 |
| 6 | 408408 |
| 7 | 2015520 |
| 8 | 9699690 |
| 9 | 45762640 |
| 10 | 212469400 |
| 11 | 973496160 |
| 12 | 4411154475 |
| 13 | 19800295200 |
| 14 | 88158457200 |
| 15 | 389753179200 |
| 16 | 1712478031110 |
| 17 | 7483097278800 |
| 18 | 32540135136600 |
| 19 | 140883148005600 |
| 20 | 607558575774150 |
| 21 | 2610765994183776 |
| 22 | 11182476723339600 |
[5,56,420,2640,15015,80080,408408,2015520,9699690, 45762640,212469400,973496160,4411154475, 19800295200,88158457200,389753179200, 1712478031110,7483097278800,32540135136600, 140883148005600,607558575774150,2610765994183776, 11182476723339600] |