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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 2 |
| 2 | 2 |
| 3 | 6 |
| 4 | 12 |
| 5 | 30 |
| 6 | 72 |
| 7 | 182 |
| 8 | 462 |
| 9 | 1190 |
| 10 | 3080 |
| 11 | 8010 |
| 12 | 20880 |
| 13 | 54522 |
| 14 | 142506 |
| 15 | 372710 |
| 16 | 975156 |
| 17 | 2552006 |
| 18 | 6679640 |
| 19 | 17484942 |
| 20 | 45771990 |
| 21 | 119825862 |
| 22 | 313697232 |
| 23 | 821252306 |
| 24 | 2150037792 |
| 25 | 5628825650 |
| 26 | 14736381842 |
| 27 | 38580227142 |
| 28 | 101004149532 |
| 29 | 264431978670 |
| 30 | 692291393640 |
| 31 | 1812441566630 |
[0,2,2,6,12,30,72,182,462,1190,3080,8010,20880, 54522,142506,372710,975156,2552006,6679640, 17484942,45771990,119825862,313697232,821252306, 2150037792,5628825650,14736381842,38580227142, 101004149532,264431978670,692291393640, 1812441566630] |