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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 12 |
| 4 | 73 |
| 5 | 584 |
| 6 | 5889 |
| 7 | 73184 |
| 8 | 1089057 |
| 9 | 19019632 |
| 10 | 384301729 |
| 11 | 8870379064 |
| 12 | 231356923985 |
| 13 | 6757908117208 |
| 14 | 219384432585553 |
| 15 | 7861969355896416 |
| 16 | 309183385066009665 |
| 17 | 13273824175564131424 |
| 18 | 619230263962630471745 |
| 19 | 31258573195774440816360 |
| 20 | 1701019508896703563600241 |
| 21 | 99446312062485160435840776 |
[1,1,3,12,73,584,5889,73184,1089057,19019632, 384301729,8870379064,231356923985,6757908117208, 219384432585553,7861969355896416, 309183385066009665,13273824175564131424, 619230263962630471745,31258573195774440816360, 1701019508896703563600241, 99446312062485160435840776] |