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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 15 |
| 5 | 54 |
| 6 | 231 |
| 7 | 1151 |
| 8 | 6544 |
| 9 | 41759 |
| 10 | 295373 |
| 11 | 2293276 |
| 12 | 19387721 |
| 13 | 177278761 |
| 14 | 1743221942 |
| 15 | 18342831993 |
| 16 | 205649438307 |
| 17 | 2447327139282 |
| 18 | 30810764360107 |
| 19 | 409126482916771 |
| 20 | 5714631215634236 |
| 21 | 83760248865355379 |
| 22 | 1285427577602987313 |
| 23 | 20613047005064025320 |
[1,1,2,5,15,54,231,1151,6544,41759,295373,2293276, 19387721,177278761,1743221942,18342831993, 205649438307,2447327139282,30810764360107, 409126482916771,5714631215634236, 83760248865355379,1285427577602987313, 20613047005064025320] |