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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 6 |
| 2 | 57 |
| 3 | 470 |
| 4 | 3756 |
| 5 | 29658 |
| 6 | 233241 |
| 7 | 1836912 |
| 8 | 14543877 |
| 9 | 116087596 |
| 10 | 936035298 |
| 11 | 7636193394 |
| 12 | 63106764294 |
| 13 | 528842660346 |
| 14 | 4497737044197 |
| 15 | 38849799300246 |
| 16 | 341016182672523 |
| 17 | 3043519729680600 |
| 18 | 27629723055323671 |
| 19 | 255224042883932790 |
[1,6,57,470,3756,29658,233241,1836912,14543877, 116087596,936035298,7636193394,63106764294, 528842660346,4497737044197,38849799300246, 341016182672523,3043519729680600, 27629723055323671,255224042883932790] |