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| n | a(n) |
|---|---|
| 0 | 2 |
| 1 | 2 |
| 2 | 20 |
| 3 | 38 |
| 4 | 146 |
| 5 | 368 |
| 6 | 1070 |
| 7 | 2824 |
| 8 | 7680 |
| 9 | 19996 |
| 10 | 53024 |
| 11 | 136350 |
| 12 | 355254 |
| 13 | 906254 |
| 14 | 2331416 |
| 15 | 5909810 |
| 16 | 15067236 |
| 17 | 37992680 |
| 18 | 96210436 |
| 19 | 241564514 |
| 20 | 608469654 |
| 21 | 1522388638 |
| 22 | 3818281784 |
| 23 | 9525139886 |
| 24 | 23806217352 |
| 25 | 59237754234 |
| 26 | 147621207142 |
| 27 | 366533832540 |
| 28 | 911151508282 |
[2,2,20,38,146,368,1070,2824,7680,19996,53024, 136350,355254,906254,2331416,5909810,15067236, 37992680,96210436,241564514,608469654,1522388638, 3818281784,9525139886,23806217352,59237754234, 147621207142,366533832540,911151508282] |