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| n | a(n) |
|---|---|
| 1 | 420 |
| 2 | 1288 |
| 3 | 3688 |
| 4 | 11728 |
| 5 | 34916 |
| 6 | 113940 |
| 7 | 348876 |
| 8 | 1158552 |
| 9 | 3626376 |
| 10 | 12193672 |
| 11 | 38853396 |
| 12 | 131871756 |
| 13 | 426383532 |
| 14 | 1457769280 |
| 15 | 4770857720 |
| 16 | 16406943392 |
| 17 | 54238894212 |
| 18 | 187427003188 |
| 19 | 624847358508 |
| 20 | 2167920197880 |
| 21 | 7278838832680 |
[420,1288,3688,11728,34916,113940,348876,1158552, 3626376,12193672,38853396,131871756,426383532, 1457769280,4770857720,16406943392,54238894212, 187427003188,624847358508,2167920197880, 7278838832680] |