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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 10 |
| 4 | 29 |
| 5 | 82 |
| 6 | 236 |
| 7 | 681 |
| 8 | 1975 |
| 9 | 5745 |
| 10 | 16757 |
| 11 | 48982 |
| 12 | 143442 |
| 13 | 420721 |
| 14 | 1235663 |
| 15 | 3633453 |
| 16 | 10695292 |
| 17 | 31511524 |
| 18 | 92919758 |
| 19 | 274203662 |
| 20 | 809719718 |
| 21 | 2392579638 |
| 22 | 7073684393 |
| 23 | 20924387460 |
| 24 | 61925598216 |
| 25 | 183350728661 |
| 26 | 543095661673 |
[1,1,4,10,29,82,236,681,1975,5745,16757,48982, 143442,420721,1235663,3633453,10695292,31511524, 92919758,274203662,809719718,2392579638, 7073684393,20924387460,61925598216,183350728661, 543095661673] |