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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 3 |
| 4 | 20 |
| 5 | 115 |
| 6 | 270 |
| 7 | 385 |
| 8 | 5240 |
| 9 | 5625 |
| 10 | 21730 |
| 11 | 300905 |
| 12 | 1290540 |
| 13 | 20688785 |
| 14 | 307710550 |
| 15 | 328399335 |
| 16 | 10177758160 |
| 17 | 178604677415 |
| 18 | 377564871150 |
| 19 | 10567221422735 |
| 20 | 43779145175540 |
| 21 | 1141273698563775 |
| 22 | 26071162562264930 |
[1,1,2,3,20,115,270,385,5240,5625,21730,300905, 1290540,20688785,307710550,328399335,10177758160, 178604677415,377564871150,10567221422735, 43779145175540,1141273698563775,26071162562264930] |