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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 31 |
| 4 | 283 |
| 5 | 3489 |
| 6 | 50913 |
| 7 | 890635 |
| 8 | 17891170 |
| 9 | 409850236 |
| 10 | 10494427982 |
| 11 | 297780829216 |
| 12 | 9261266862273 |
| 13 | 313453533534739 |
| 14 | 11464487066049791 |
| 15 | 450644378868285130 |
| 16 | 18942868694407904729 |
| 17 | 847930346323808122469 |
| 18 | 40266107916200371331007 |
| 19 | 2021842180288047801103956 |
[1,1,4,31,283,3489,50913,890635,17891170, 409850236,10494427982,297780829216,9261266862273, 313453533534739,11464487066049791, 450644378868285130,18942868694407904729, 847930346323808122469,40266107916200371331007, 2021842180288047801103956] |