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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 12 |
| 5 | 28 |
| 6 | 91 |
| 7 | 242 |
| 8 | 839 |
| 9 | 2416 |
| 10 | 8782 |
| 11 | 26700 |
| 12 | 100437 |
| 13 | 317981 |
| 14 | 1226766 |
| 15 | 4010820 |
| 16 | 15782053 |
| 17 | 52955735 |
| 18 | 211754709 |
| 19 | 725756163 |
| 20 | 2941028924 |
| 21 | 10260046434 |
| 22 | 42043257062 |
| 23 | 148908505647 |
| 24 | 615994366991 |
| 25 | 2210482944544 |
| 26 | 9219230935633 |
| 27 | 33462915243756 |
| 28 | 140563142274370 |
| 29 | 515352054090757 |
| 30 | 2178406144490742 |
[1,1,2,4,12,28,91,242,839,2416,8782,26700,100437, 317981,1226766,4010820,15782053,52955735, 211754709,725756163,2941028924,10260046434, 42043257062,148908505647,615994366991, 2210482944544,9219230935633,33462915243756, 140563142274370,515352054090757,2178406144490742] |