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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 10 |
| 4 | 34 |
| 5 | 218 |
| 6 | 1708 |
| 7 | 12556 |
| 8 | 97340 |
| 9 | 1139932 |
| 10 | 12602584 |
| 11 | 142757624 |
| 12 | 1983086488 |
| 13 | 26745019000 |
| 14 | 402951386576 |
| 15 | 7181178238672 |
| 16 | 115410887636752 |
| 17 | 2039658743085584 |
| 18 | 42354537803172640 |
| 19 | 815690033731561888 |
| 20 | 17593347085888752416 |
| 21 | 416765224159172991136 |
| 22 | 9379433694333768563392 |
[1,1,2,10,34,218,1708,12556,97340,1139932, 12602584,142757624,1983086488,26745019000, 402951386576,7181178238672,115410887636752, 2039658743085584,42354537803172640, 815690033731561888,17593347085888752416, 416765224159172991136,9379433694333768563392] |