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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 7 |
| 4 | 26 |
| 5 | 102 |
| 6 | 424 |
| 7 | 1827 |
| 8 | 8078 |
| 9 | 36466 |
| 10 | 167376 |
| 11 | 778718 |
| 12 | 3664164 |
| 13 | 17407068 |
| 14 | 83375616 |
| 15 | 402198915 |
| 16 | 1952296598 |
| 17 | 9528757098 |
| 18 | 46735576816 |
| 19 | 230227356906 |
| 20 | 1138609205372 |
| 21 | 5651170500612 |
| 22 | 28138939936704 |
| 23 | 140527262919342 |
| 24 | 703704207921932 |
| 25 | 3532664478314484 |
| 26 | 17775185122527776 |
[1,1,2,7,26,102,424,1827,8078,36466,167376,778718, 3664164,17407068,83375616,402198915,1952296598, 9528757098,46735576816,230227356906,1138609205372, 5651170500612,28138939936704,140527262919342, 703704207921932,3532664478314484, 17775185122527776] |