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| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 16 |
| 3 | 57 |
| 4 | 213 |
| 5 | 796 |
| 6 | 2964 |
| 7 | 11049 |
| 8 | 41193 |
| 9 | 153556 |
| 10 | 572424 |
| 11 | 2133897 |
| 12 | 7954765 |
| 13 | 29653852 |
| 14 | 110543980 |
| 15 | 412087129 |
| 16 | 1536183105 |
| 17 | 5726601012 |
| 18 | 21347689024 |
| 19 | 79580160153 |
| 20 | 296659834437 |
| 21 | 1105891936092 |
| 22 | 4122556653316 |
| 23 | 15368114012745 |
| 24 | 57289431819225 |
[4,16,57,213,796,2964,11049,41193,153556,572424, 2133897,7954765,29653852,110543980,412087129, 1536183105,5726601012,21347689024,79580160153, 296659834437,1105891936092,4122556653316, 15368114012745,57289431819225] |