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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 7 |
| 5 | 26 |
| 6 | 124 |
| 7 | 596 |
| 8 | 3365 |
| 9 | 18954 |
| 10 | 120242 |
| 11 | 760140 |
| 12 | 5281436 |
| 13 | 36617556 |
| 14 | 274624708 |
| 15 | 2059397032 |
| 16 | 16520347463 |
| 17 | 132773992954 |
| 18 | 1132184343204 |
| 19 | 9689336590700 |
| 20 | 87424470404886 |
| 21 | 792807348829740 |
| 22 | 7541745922428356 |
| 23 | 72187384283011000 |
[1,1,2,7,26,124,596,3365,18954,120242,760140, 5281436,36617556,274624708,2059397032,16520347463, 132773992954,1132184343204,9689336590700, 87424470404886,792807348829740,7541745922428356, 72187384283011000] |