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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 6 |
| 4 | 17 |
| 5 | 100 |
| 6 | 529 |
| 7 | 3766 |
| 8 | 31121 |
| 9 | 276984 |
| 10 | 2755553 |
| 11 | 29665306 |
| 12 | 364627801 |
| 13 | 4639937380 |
| 14 | 64952094401 |
| 15 | 973467571350 |
| 16 | 15750475301921 |
| 17 | 264870218828656 |
| 18 | 4759194994114369 |
| 19 | 90124395399063730 |
| 20 | 1812001488739061417 |
| 21 | 37956199941196210716 |
| 22 | 832297726351555617569 |
[1,1,1,6,17,100,529,3766,31121,276984,2755553, 29665306,364627801,4639937380,64952094401, 973467571350,15750475301921,264870218828656, 4759194994114369,90124395399063730, 1812001488739061417,37956199941196210716, 832297726351555617569] |