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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 6 |
| 3 | 37 |
| 4 | 268 |
| 5 | 2620 |
| 6 | 23522 |
| 7 | 223445 |
| 8 | 2117743 |
| 9 | 20154626 |
| 10 | 192105610 |
| 11 | 1831726755 |
| 12 | 17471097262 |
| 13 | 166653939139 |
| 14 | 1589761562086 |
| 15 | 15165501199167 |
| 16 | 144672176026087 |
| 17 | 1380113732256295 |
| 18 | 13165743488534979 |
| 19 | 125596111620967559 |
[0,6,37,268,2620,23522,223445,2117743,20154626, 192105610,1831726755,17471097262,166653939139, 1589761562086,15165501199167,144672176026087, 1380113732256295,13165743488534979, 125596111620967559] |