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| n | a(n) |
|---|---|
| 0 | 2 |
| 1 | 4 |
| 2 | 8 |
| 3 | 18 |
| 4 | 40 |
| 5 | 92 |
| 6 | 210 |
| 7 | 484 |
| 8 | 1112 |
| 9 | 2562 |
| 10 | 5896 |
| 11 | 13580 |
| 12 | 31266 |
| 13 | 72004 |
| 14 | 165800 |
| 15 | 381810 |
| 16 | 879208 |
| 17 | 2024636 |
| 18 | 4662258 |
| 19 | 10736164 |
| 20 | 24722936 |
| 21 | 56931426 |
| 22 | 131100232 |
| 23 | 301894508 |
| 24 | 695195202 |
| 25 | 1600878724 |
| 26 | 3686464328 |
| 27 | 8489100498 |
| 28 | 19548493480 |
| 29 | 45015794972 |
| 30 | 103661275410 |
[2,4,8,18,40,92,210,484,1112,2562,5896,13580, 31266,72004,165800,381810,879208,2024636,4662258, 10736164,24722936,56931426,131100232,301894508, 695195202,1600878724,3686464328,8489100498, 19548493480,45015794972,103661275410] |