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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 9 |
| 4 | 32 |
| 5 | 103 |
| 6 | 361 |
| 7 | 1307 |
| 8 | 4792 |
| 9 | 18033 |
| 10 | 68631 |
| 11 | 265451 |
| 12 | 1034256 |
| 13 | 4083197 |
| 14 | 16204618 |
| 15 | 64889975 |
| 16 | 261337858 |
| 17 | 1058251013 |
| 18 | 4309632977 |
| 19 | 17616277293 |
| 20 | 72364546556 |
| 21 | 298151009423 |
| 22 | 1233408725210 |
| 23 | 5115914210353 |
| 24 | 21288345954796 |
| 25 | 88803907834511 |
| 26 | 371383647629043 |
| 27 | 1556761843796677 |
| 28 | 6538881650516046 |
[1,1,4,9,32,103,361,1307,4792,18033,68631,265451, 1034256,4083197,16204618,64889975,261337858, 1058251013,4309632977,17616277293,72364546556, 298151009423,1233408725210,5115914210353, 21288345954796,88803907834511,371383647629043, 1556761843796677,6538881650516046] |