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| n | a(n) |
|---|---|
| 1 | 4568 |
| 2 | 9108 |
| 3 | 17312 |
| 4 | 41832 |
| 5 | 93680 |
| 6 | 254784 |
| 7 | 639440 |
| 8 | 1878960 |
| 9 | 5098448 |
| 10 | 15829008 |
| 11 | 45291152 |
| 12 | 146459472 |
| 13 | 434549840 |
| 14 | 1448936784 |
| 15 | 4409332880 |
| 16 | 15047298000 |
| 17 | 46627861328 |
| 18 | 161947291728 |
| 19 | 508508258192 |
| 20 | 1789849512912 |
| 21 | 5675323653200 |
[4568,9108,17312,41832,93680,254784,639440, 1878960,5098448,15829008,45291152,146459472, 434549840,1448936784,4409332880,15047298000, 46627861328,161947291728,508508258192, 1789849512912,5675323653200] |