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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 12 |
| 4 | 39 |
| 5 | 148 |
| 6 | 550 |
| 7 | 2073 |
| 8 | 8163 |
| 9 | 32415 |
| 10 | 128870 |
| 11 | 521964 |
| 12 | 2131786 |
| 13 | 8718262 |
| 14 | 35959256 |
| 15 | 149267043 |
| 16 | 620741014 |
| 17 | 2592823626 |
| 18 | 10879365183 |
| 19 | 45738855833 |
| 20 | 192807224404 |
| 21 | 815333606093 |
| 22 | 3454225929696 |
| 23 | 14661217666256 |
| 24 | 62368650443349 |
| 25 | 265747561015488 |
| 26 | 1133948758531347 |
| 27 | 4846603982947246 |
[1,1,4,12,39,148,550,2073,8163,32415,128870, 521964,2131786,8718262,35959256,149267043, 620741014,2592823626,10879365183,45738855833, 192807224404,815333606093,3454225929696, 14661217666256,62368650443349,265747561015488, 1133948758531347,4846603982947246] |