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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 7 |
| 3 | 24 |
| 4 | 99 |
| 5 | 403 |
| 6 | 1754 |
| 7 | 7685 |
| 8 | 34615 |
| 9 | 157138 |
| 10 | 724092 |
| 11 | 3359140 |
| 12 | 15717016 |
| 13 | 73961981 |
| 14 | 349987423 |
| 15 | 1663258901 |
| 16 | 7936993440 |
| 17 | 37999635136 |
| 18 | 182481367565 |
| 19 | 878650252569 |
| 20 | 4240640613099 |
| 21 | 20509555802674 |
| 22 | 99383747822983 |
| 23 | 482402000559299 |
| 24 | 2345172245872755 |
| 25 | 11417146504183784 |
| 26 | 55653887338699863 |
| 27 | 271608882010579778 |
[1,2,7,24,99,403,1754,7685,34615,157138,724092, 3359140,15717016,73961981,349987423,1663258901, 7936993440,37999635136,182481367565,878650252569, 4240640613099,20509555802674,99383747822983, 482402000559299,2345172245872755, 11417146504183784,55653887338699863, 271608882010579778] |