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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 15 |
| 4 | 65 |
| 5 | 298 |
| 6 | 1429 |
| 7 | 7073 |
| 8 | 35869 |
| 9 | 185403 |
| 10 | 973198 |
| 11 | 5173644 |
| 12 | 27797914 |
| 13 | 150715321 |
| 14 | 823541564 |
| 15 | 4530609391 |
| 16 | 25073291597 |
| 17 | 139492998775 |
| 18 | 779706274423 |
| 19 | 4376600956063 |
| 20 | 24659875131049 |
| 21 | 139424357994344 |
| 22 | 790763858547445 |
| 23 | 4497788153203946 |
| 24 | 25650342635871106 |
[1,1,4,15,65,298,1429,7073,35869,185403,973198, 5173644,27797914,150715321,823541564,4530609391, 25073291597,139492998775,779706274423, 4376600956063,24659875131049,139424357994344, 790763858547445,4497788153203946, 25650342635871106] |