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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 10 |
| 4 | 50 |
| 5 | 200 |
| 6 | 1250 |
| 7 | 6850 |
| 8 | 51850 |
| 9 | 360100 |
| 10 | 3211850 |
| 11 | 26978450 |
| 12 | 277502750 |
| 13 | 2732541700 |
| 14 | 31870330450 |
| 15 | 359775334450 |
| 16 | 4694140275650 |
| 17 | 59739766446500 |
| 18 | 862437753582650 |
| 19 | 12212993378417650 |
| 20 | 193324921630774150 |
| 21 | 3014526392045251300 |
| 22 | 51925731564631111250 |
| 23 | 883935015769120470050 |
[1,4,10,50,200,1250,6850,51850,360100,3211850, 26978450,277502750,2732541700,31870330450, 359775334450,4694140275650,59739766446500, 862437753582650,12212993378417650, 193324921630774150,3014526392045251300, 51925731564631111250,883935015769120470050] |