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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 4 |
| 3 | 12 |
| 4 | 34 |
| 5 | 89 |
| 6 | 226 |
| 7 | 554 |
| 8 | 1328 |
| 9 | 3104 |
| 10 | 7158 |
| 11 | 16235 |
| 12 | 36420 |
| 13 | 80797 |
| 14 | 177789 |
| 15 | 387968 |
| 16 | 841696 |
| 17 | 1814473 |
| 18 | 3892920 |
| 19 | 8313588 |
| 20 | 17686711 |
| 21 | 37486091 |
| 22 | 79213997 |
| 23 | 166888364 |
| 24 | 350720648 |
| 25 | 735273025 |
| 26 | 1538259673 |
| 27 | 3211682091 |
| 28 | 6693935172 |
| 29 | 13928034709 |
| 30 | 28936571039 |
| 31 | 60032053097 |
[0,1,4,12,34,89,226,554,1328,3104,7158,16235, 36420,80797,177789,387968,841696,1814473,3892920, 8313588,17686711,37486091,79213997,166888364, 350720648,735273025,1538259673,3211682091, 6693935172,13928034709,28936571039,60032053097] |