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| n | a(n) |
|---|---|
| 2 | 2 |
| 3 | 6 |
| 4 | 22 |
| 5 | 106 |
| 6 | 630 |
| 7 | 4394 |
| 8 | 35078 |
| 9 | 315258 |
| 10 | 3149494 |
| 11 | 34620010 |
| 12 | 415222566 |
| 13 | 5395737242 |
| 14 | 75516784982 |
| 15 | 1132471183626 |
| 16 | 18115911832390 |
| 17 | 307919970965434 |
| 18 | 5541804787940598 |
| 19 | 105282261866132138 |
| 20 | 2105441434230129254 |
| 21 | 44210612765653749210 |
| 22 | 972564180363044943766 |
[2,6,22,106,630,4394,35078,315258,3149494, 34620010,415222566,5395737242,75516784982, 1132471183626,18115911832390,307919970965434, 5541804787940598,105282261866132138, 2105441434230129254,44210612765653749210, 972564180363044943766] |