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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 5 |
| 2 | 40 |
| 3 | 380 |
| 4 | 3970 |
| 5 | 44051 |
| 6 | 509575 |
| 7 | 6077435 |
| 8 | 74194780 |
| 9 | 922644310 |
| 10 | 11646083631 |
| 11 | 148827827450 |
| 12 | 1921724362880 |
| 13 | 25034267112600 |
| 14 | 328614891689845 |
| 15 | 4342322118727300 |
| 16 | 57715241768897445 |
| 17 | 771087466276360970 |
| 18 | 10349495416322497575 |
| 19 | 139486475071720234920 |
| 20 | 1886980259513934080860 |
| 21 | 25613816043115261657425 |
[1,5,40,380,3970,44051,509575,6077435,74194780, 922644310,11646083631,148827827450,1921724362880, 25034267112600,328614891689845,4342322118727300, 57715241768897445,771087466276360970, 10349495416322497575,139486475071720234920, 1886980259513934080860,25613816043115261657425] |