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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 6 |
| 4 | 13 |
| 5 | 37 |
| 6 | 31 |
| 7 | 605 |
| 8 | 1411 |
| 9 | 7174 |
| 10 | 15567 |
| 11 | 608953 |
| 12 | 78903 |
| 13 | 334535 |
| 14 | 611552 |
| 15 | 105928 |
| 16 | 2557047 |
| 17 | 2979162 |
| 18 | 3263358 |
| 19 | 6242520 |
| 20 | 7825254 |
| 21 | 37404834 |
| 22 | 267494881 |
| 23 | 639174488 |
[1,1,6,13,37,31,605,1411,7174,15567,608953,78903, 334535,611552,105928,2557047,2979162,3263358, 6242520,7825254,37404834,267494881,639174488] |