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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 5 |
| 3 | 15 |
| 4 | 50 |
| 5 | 175 |
| 6 | 643 |
| 7 | 2442 |
| 8 | 9497 |
| 9 | 37772 |
| 10 | 152757 |
| 11 | 626466 |
| 12 | 2602060 |
| 13 | 10918685 |
| 14 | 46235865 |
| 15 | 197396778 |
| 16 | 848640258 |
| 17 | 3671712505 |
| 18 | 15976961310 |
| 19 | 69874586990 |
| 20 | 307024031593 |
| 21 | 1354759662530 |
| 22 | 6001007238525 |
| 23 | 26676880710809 |
| 24 | 118977537295689 |
| 25 | 532239704904251 |
| 26 | 2387650011379440 |
| 27 | 10739032580822009 |
[1,2,5,15,50,175,643,2442,9497,37772,152757, 626466,2602060,10918685,46235865,197396778, 848640258,3671712505,15976961310,69874586990, 307024031593,1354759662530,6001007238525, 26676880710809,118977537295689,532239704904251, 2387650011379440,10739032580822009] |