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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 6 |
| 4 | 20 |
| 5 | 57 |
| 6 | 196 |
| 7 | 668 |
| 8 | 2393 |
| 9 | 8767 |
| 10 | 32685 |
| 11 | 123971 |
| 12 | 475817 |
| 13 | 1847493 |
| 14 | 7237415 |
| 15 | 28604348 |
| 16 | 113831462 |
| 17 | 456068443 |
| 18 | 1837914610 |
| 19 | 7444900802 |
| 20 | 30305229024 |
| 21 | 123883817163 |
| 22 | 508434835137 |
| 23 | 2094251103092 |
| 24 | 8654631662005 |
| 25 | 35875740152914 |
| 26 | 149133744596402 |
| 27 | 621558342327013 |
| 28 | 2596840502079358 |
[1,1,3,6,20,57,196,668,2393,8767,32685,123971, 475817,1847493,7237415,28604348,113831462, 456068443,1837914610,7444900802,30305229024, 123883817163,508434835137,2094251103092, 8654631662005,35875740152914,149133744596402, 621558342327013,2596840502079358] |