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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 12 |
| 5 | 34 |
| 6 | 115 |
| 7 | 381 |
| 8 | 1382 |
| 9 | 5021 |
| 10 | 19107 |
| 11 | 73516 |
| 12 | 290271 |
| 13 | 1160122 |
| 14 | 4711298 |
| 15 | 19347457 |
| 16 | 80345025 |
| 17 | 336732077 |
| 18 | 1423193019 |
| 19 | 6060568351 |
| 20 | 25982989222 |
| 21 | 112079577365 |
| 22 | 486135477158 |
| 23 | 2119306304250 |
| 24 | 9281909110795 |
| 25 | 40825347704860 |
| 26 | 180268378930116 |
| 27 | 798880428292549 |
| 28 | 3552224088304126 |
[1,1,2,4,12,34,115,381,1382,5021,19107,73516, 290271,1160122,4711298,19347457,80345025, 336732077,1423193019,6060568351,25982989222, 112079577365,486135477158,2119306304250, 9281909110795,40825347704860,180268378930116, 798880428292549,3552224088304126] |