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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 5 |
| 2 | 30 |
| 3 | 155 |
| 4 | 805 |
| 5 | 4055 |
| 6 | 20455 |
| 7 | 102455 |
| 8 | 513230 |
| 9 | 2567230 |
| 10 | 12841130 |
| 11 | 64211380 |
| 12 | 321082905 |
| 13 | 1605444405 |
| 14 | 8027354055 |
| 15 | 40136925680 |
| 16 | 200685295955 |
| 17 | 1003427268205 |
| 18 | 5017139711105 |
| 19 | 25085702537730 |
| 20 | 125428529603755 |
| 21 | 627142668099880 |
| 22 | 3135713425289030 |
| 23 | 15678567227192655 |
[1,5,30,155,805,4055,20455,102455,513230,2567230, 12841130,64211380,321082905,1605444405,8027354055, 40136925680,200685295955,1003427268205, 5017139711105,25085702537730,125428529603755, 627142668099880,3135713425289030, 15678567227192655] |