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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | 2 |
| 4 | 3 |
| 5 | 20 |
| 6 | 55 |
| 7 | 210 |
| 8 | 1225 |
| 9 | 4760 |
| 10 | 26145 |
| 11 | 157850 |
| 12 | 811195 |
| 13 | 5345340 |
| 14 | 35170135 |
| 15 | 222472250 |
| 16 | 1650073425 |
| 17 | 12000388400 |
| 18 | 88563700225 |
| 19 | 720929459250 |
| 20 | 5786843137075 |
| 21 | 48072795270500 |
| 22 | 424314078763575 |
| 23 | 3731123025279650 |
| 24 | 34084058218435225 |
| 25 | 323768324084205000 |
[1,0,1,2,3,20,55,210,1225,4760,26145,157850, 811195,5345340,35170135,222472250,1650073425, 12000388400,88563700225,720929459250, 5786843137075,48072795270500,424314078763575, 3731123025279650,34084058218435225, 323768324084205000] |