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| n | a(n) |
|---|---|
| 1 | 21 |
| 2 | 2292 |
| 3 | 50028 |
| 4 | 505154 |
| 5 | 3213429 |
| 6 | 15002490 |
| 7 | 56118016 |
| 8 | 177725772 |
| 9 | 494492733 |
| 10 | 1240508808 |
| 11 | 2859421884 |
| 12 | 6142632990 |
| 13 | 12432735341 |
| 14 | 23913080862 |
| 15 | 44008420512 |
| 16 | 77925990328 |
| 17 | 133371203589 |
| 18 | 221477260860 |
| 19 | 357993503916 |
| 20 | 564783216666 |
[21,2292,50028,505154,3213429,15002490,56118016, 177725772,494492733,1240508808,2859421884, 6142632990,12432735341,23913080862,44008420512, 77925990328,133371203589,221477260860, 357993503916,564783216666] |