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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 7 |
| 4 | 32 |
| 5 | 175 |
| 6 | 1086 |
| 7 | 7429 |
| 8 | 54994 |
| 9 | 435120 |
| 10 | 3647686 |
| 11 | 32192596 |
| 12 | 297654824 |
| 13 | 2872372828 |
| 14 | 28841766844 |
| 15 | 300592170551 |
| 16 | 3244942353856 |
| 17 | 36219458512421 |
| 18 | 417365572999944 |
| 19 | 4958429472475171 |
| 20 | 60659660219655616 |
| 21 | 763325035692109389 |
[1,1,2,7,32,175,1086,7429,54994,435120,3647686, 32192596,297654824,2872372828,28841766844, 300592170551,3244942353856,36219458512421, 417365572999944,4958429472475171, 60659660219655616,763325035692109389] |