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| n | a(n) |
|---|---|
| 1 | 13 |
| 2 | 76 |
| 3 | 521 |
| 4 | 3288 |
| 5 | 20400 |
| 6 | 123976 |
| 7 | 742688 |
| 8 | 4397376 |
| 9 | 25791040 |
| 10 | 150081504 |
| 11 | 867569920 |
| 12 | 4986765312 |
| 13 | 28523566592 |
| 14 | 162453499008 |
| 15 | 921756644864 |
| 16 | 5212543265792 |
| 17 | 29388948548608 |
| 18 | 165253519908352 |
| 19 | 926962234179584 |
| 20 | 5188178346090496 |
[13,76,521,3288,20400,123976,742688,4397376, 25791040,150081504,867569920,4986765312, 28523566592,162453499008,921756644864, 5212543265792,29388948548608,165253519908352, 926962234179584,5188178346090496] |