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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 5 |
| 2 | 30 |
| 3 | 185 |
| 4 | 1140 |
| 5 | 7025 |
| 6 | 43290 |
| 7 | 266765 |
| 8 | 1643880 |
| 9 | 10130045 |
| 10 | 62424150 |
| 11 | 384674945 |
| 12 | 2370473820 |
| 13 | 14607517865 |
| 14 | 90015581010 |
| 15 | 554701003925 |
| 16 | 3418221604560 |
| 17 | 21064030631285 |
| 18 | 129802405392270 |
| 19 | 799878462984905 |
| 20 | 4929073183301700 |
[1,5,30,185,1140,7025,43290,266765,1643880, 10130045,62424150,384674945,2370473820, 14607517865,90015581010,554701003925, 3418221604560,21064030631285,129802405392270, 799878462984905,4929073183301700] |