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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 7 |
| 2 | 43 |
| 3 | 264 |
| 4 | 1621 |
| 5 | 9953 |
| 6 | 61112 |
| 7 | 375231 |
| 8 | 2303939 |
| 9 | 14146313 |
| 10 | 86859145 |
| 11 | 533319959 |
| 12 | 3274614074 |
| 13 | 20106311704 |
| 14 | 123453866991 |
| 15 | 758013577995 |
| 16 | 4654245334143 |
| 17 | 28577324020619 |
| 18 | 175466351588409 |
| 19 | 1077373112945523 |
| 20 | 6615130559166437 |
| 21 | 40617267861064920 |
| 22 | 249392273325801363 |
[1,7,43,264,1621,9953,61112,375231,2303939, 14146313,86859145,533319959,3274614074, 20106311704,123453866991,758013577995, 4654245334143,28577324020619,175466351588409, 1077373112945523,6615130559166437, 40617267861064920,249392273325801363] |