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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | 1 |
| 4 | 2 |
| 5 | 5 |
| 6 | 13 |
| 7 | 36 |
| 8 | 109 |
| 9 | 359 |
| 10 | 1266 |
| 11 | 4731 |
| 12 | 18657 |
| 13 | 77464 |
| 14 | 337681 |
| 15 | 1540381 |
| 16 | 7330418 |
| 17 | 36301105 |
| 18 | 186688845 |
| 19 | 995293580 |
| 20 | 5491595645 |
| 21 | 31310124067 |
| 22 | 184199228226 |
| 23 | 1116717966103 |
| 24 | 6968515690273 |
| 25 | 44710457783760 |
| 26 | 294655920067105 |
| 27 | 1992750830574681 |
| 28 | 13817968813639426 |
[1,0,1,1,2,5,13,36,109,359,1266,4731,18657,77464, 337681,1540381,7330418,36301105,186688845, 995293580,5491595645,31310124067,184199228226, 1116717966103,6968515690273,44710457783760, 294655920067105,1992750830574681, 13817968813639426] |