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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 15 |
| 3 | 80 |
| 4 | 109 |
| 5 | 1718 |
| 6 | 987 |
| 7 | 29804 |
| 8 | 6833 |
| 9 | 503754 |
| 10 | 61471 |
| 11 | 8196000 |
| 12 | 446685 |
| 13 | 132869478 |
| 14 | 4044683 |
| 15 | 2135349340 |
| 16 | 28010209 |
| 17 | 34275691290 |
| 18 | 252075183 |
| 19 | 548965769712 |
| 20 | 1832196621 |
| 21 | 8790562745814 |
| 22 | 16523720315 |
| 23 | 140687644563596 |
| 24 | 114063811921 |
| 25 | 2251453327265770 |
| 26 | 1038913441855 |
[1,2,15,80,109,1718,987,29804,6833,503754,61471, 8196000,446685,132869478,4044683,2135349340, 28010209,34275691290,252075183,548965769712, 1832196621,8790562745814,16523720315, 140687644563596,114063811921,2251453327265770, 1038913441855] |