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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 9 |
| 4 | 39 |
| 5 | 112 |
| 6 | 512 |
| 7 | 1660 |
| 8 | 7778 |
| 9 | 27188 |
| 10 | 129401 |
| 11 | 475825 |
| 12 | 2288259 |
| 13 | 8728352 |
| 14 | 42284402 |
| 15 | 165826745 |
| 16 | 807712214 |
| 17 | 3237235537 |
| 18 | 15833338030 |
| 19 | 64579379484 |
| 20 | 316882110960 |
| 21 | 1311217629144 |
| 22 | 6450625830056 |
| 23 | 27015741085305 |
| 24 | 133185518215086 |
| 25 | 563537265001788 |
| 26 | 2783016272151599 |
| 27 | 11879828894712115 |
| 28 | 58753259096839334 |
[1,1,4,9,39,112,512,1660,7778,27188,129401,475825, 2288259,8728352,42284402,165826745,807712214, 3237235537,15833338030,64579379484,316882110960, 1311217629144,6450625830056,27015741085305, 133185518215086,563537265001788,2783016272151599, 11879828894712115,58753259096839334] |