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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 8 |
| 3 | 50 |
| 4 | 301 |
| 5 | 1808 |
| 6 | 10850 |
| 7 | 65101 |
| 8 | 390608 |
| 9 | 2343650 |
| 10 | 14061901 |
| 11 | 84371408 |
| 12 | 506228450 |
| 13 | 3037370701 |
| 14 | 18224224208 |
| 15 | 109345345250 |
| 16 | 656072071501 |
| 17 | 3936432429008 |
| 18 | 23618594574050 |
| 19 | 141711567444301 |
| 20 | 850269404665808 |
| 21 | 5101616427994850 |
[1,8,50,301,1808,10850,65101,390608,2343650, 14061901,84371408,506228450,3037370701, 18224224208,109345345250,656072071501, 3936432429008,23618594574050,141711567444301, 850269404665808,5101616427994850] |