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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 7 |
| 4 | 25 |
| 5 | 92 |
| 6 | 359 |
| 7 | 1453 |
| 8 | 6018 |
| 9 | 25411 |
| 10 | 109032 |
| 11 | 473942 |
| 12 | 2082550 |
| 13 | 9235675 |
| 14 | 41284297 |
| 15 | 185819487 |
| 16 | 841433773 |
| 17 | 3830604764 |
| 18 | 17521832924 |
| 19 | 80490034307 |
| 20 | 371169646860 |
| 21 | 1717567062240 |
| 22 | 7973153760616 |
| 23 | 37119622029816 |
| 24 | 173272771061677 |
| 25 | 810810134833720 |
| 26 | 3802675087749650 |
[1,1,2,7,25,92,359,1453,6018,25411,109032,473942, 2082550,9235675,41284297,185819487,841433773, 3830604764,17521832924,80490034307,371169646860, 1717567062240,7973153760616,37119622029816, 173272771061677,810810134833720,3802675087749650] |