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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 1 |
| 3 | 10 |
| 4 | 17 |
| 5 | 126 |
| 6 | 262 |
| 7 | 1716 |
| 8 | 3985 |
| 9 | 24310 |
| 10 | 60626 |
| 11 | 352716 |
| 12 | 925190 |
| 13 | 5200300 |
| 14 | 14168988 |
| 15 | 77558760 |
| 16 | 217721745 |
| 17 | 1166803110 |
| 18 | 3355615450 |
| 19 | 17672631900 |
| 20 | 51855874642 |
| 21 | 269128937220 |
| 22 | 803232328548 |
| 23 | 4116715363800 |
| 24 | 12467572005382 |
| 25 | 63205303218876 |
| 26 | 193873026294052 |
[0,1,1,10,17,126,262,1716,3985,24310,60626,352716, 925190,5200300,14168988,77558760,217721745, 1166803110,3355615450,17672631900,51855874642, 269128937220,803232328548,4116715363800, 12467572005382,63205303218876,193873026294052] |