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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 4 |
| 4 | 5 |
| 5 | 21 |
| 6 | 28 |
| 7 | 36 |
| 8 | 165 |
| 9 | 220 |
| 10 | 1001 |
| 11 | 1365 |
| 12 | 1820 |
| 13 | 8568 |
| 14 | 11628 |
| 15 | 54264 |
| 16 | 74613 |
| 17 | 346104 |
| 18 | 480700 |
| 19 | 657800 |
| 20 | 3108105 |
| 21 | 4292145 |
| 22 | 20160075 |
| 23 | 28048800 |
| 24 | 38567100 |
| 25 | 183579396 |
| 26 | 254186856 |
| 27 | 1203322288 |
| 28 | 1676056044 |
| 29 | 7898654920 |
| 30 | 11058116888 |
[1,1,1,4,5,21,28,36,165,220,1001,1365,1820,8568, 11628,54264,74613,346104,480700,657800,3108105, 4292145,20160075,28048800,38567100,183579396, 254186856,1203322288,1676056044,7898654920, 11058116888] |