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| n | a(n) |
|---|---|
| 1 | 6 |
| 2 | 152 |
| 3 | 1947 |
| 4 | 17352 |
| 5 | 121520 |
| 6 | 712406 |
| 7 | 3633649 |
| 8 | 16547278 |
| 9 | 68531079 |
| 10 | 261693631 |
| 11 | 931194981 |
| 12 | 3113638802 |
| 13 | 9849622993 |
| 14 | 29642927267 |
| 15 | 85271613063 |
| 16 | 235393492799 |
| 17 | 625708778733 |
| 18 | 1606286648601 |
| 19 | 3992748071821 |
| 20 | 9631887926896 |
| 21 | 22595573914587 |
[6,152,1947,17352,121520,712406,3633649,16547278, 68531079,261693631,931194981,3113638802, 9849622993,29642927267,85271613063,235393492799, 625708778733,1606286648601,3992748071821, 9631887926896,22595573914587] |