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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 17 |
| 5 | 133 |
| 6 | 1313 |
| 7 | 15623 |
| 8 | 217409 |
| 9 | 3462921 |
| 10 | 62115169 |
| 11 | 1238840459 |
| 12 | 27192374929 |
| 13 | 651378157837 |
| 14 | 16908639728833 |
| 15 | 472790534249487 |
| 16 | 14166807387755777 |
| 17 | 452865045873935377 |
| 18 | 15383244752326047041 |
| 19 | 553343946037863758099 |
| 20 | 21011686704686496760721 |
[1,1,3,17,133,1313,15623,217409,3462921,62115169, 1238840459,27192374929,651378157837, 16908639728833,472790534249487,14166807387755777, 452865045873935377,15383244752326047041, 553343946037863758099,21011686704686496760721] |