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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 7 |
| 3 | 55 |
| 4 | 469 |
| 5 | 4307 |
| 6 | 41678 |
| 7 | 418872 |
| 8 | 4330275 |
| 9 | 45754091 |
| 10 | 491916135 |
| 11 | 5364166402 |
| 12 | 59186372395 |
| 13 | 659556170091 |
| 14 | 7412556531714 |
| 15 | 83921355689635 |
| 16 | 956228695216241 |
| 17 | 10957322339242547 |
| 18 | 126189988012692329 |
| 19 | 1459793848341094130 |
| 20 | 16955390069787782159 |
| 21 | 197653935181097885580 |
[1,1,7,55,469,4307,41678,418872,4330275,45754091, 491916135,5364166402,59186372395,659556170091, 7412556531714,83921355689635,956228695216241, 10957322339242547,126189988012692329, 1459793848341094130,16955390069787782159, 197653935181097885580] |