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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 30 |
| 4 | 30 |
| 5 | 165 |
| 6 | 15015 |
| 7 | 36465 |
| 8 | 62985 |
| 9 | 7436429 |
| 10 | 11849255 |
| 11 | 73465381 |
| 12 | 33426748355 |
| 13 | 50708377254535 |
| 14 | 436092044389001 |
| 15 | 1863302371480277 |
| 16 | 1086305282573001491 |
| 17 | 64092011671807087969 |
| 18 | 3909612711980232366109 |
| 19 | 8449808119441147371913 |
| 20 | 18598027670889965365580513 |
| 21 | 3543193335582015099413 |
[1,1,30,30,165,15015,36465,62985,7436429,11849255, 73465381,33426748355,50708377254535, 436092044389001,1863302371480277, 1086305282573001491,64092011671807087969, 3909612711980232366109,8449808119441147371913, 18598027670889965365580513,3543193335582015099413] |