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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 6 |
| 5 | 25 |
| 6 | 60 |
| 7 | 210 |
| 8 | 1400 |
| 9 | 7560 |
| 10 | 12600 |
| 11 | 69300 |
| 12 | 693000 |
| 13 | 5405400 |
| 14 | 46666620 |
| 15 | 37837800 |
| 16 | 302702400 |
| 17 | 4288284000 |
| 18 | 46313467200 |
| 19 | 542639457360 |
| 20 | 5768599636800 |
| 21 | 2053230379200 |
| 22 | 22585534171200 |
| 23 | 432889404948000 |
| 24 | 6233607431251200 |
| 25 | 96101447898456000 |
| 26 | 1328104694380464000 |
[1,1,1,3,6,25,60,210,1400,7560,12600,69300,693000, 5405400,46666620,37837800,302702400,4288284000, 46313467200,542639457360,5768599636800, 2053230379200,22585534171200,432889404948000, 6233607431251200,96101447898456000, 1328104694380464000] |