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| n | a(n) |
|---|---|
| 1 | -1 |
| 2 | 3 |
| 3 | 4 |
| 4 | 6 |
| 5 | 8 |
| 6 | 12 |
| 7 | -1 |
| 8 | 24 |
| 9 | 30 |
| 10 | 32 |
| 11 | -1 |
| 12 | 48 |
| 13 | 60 |
| 14 | -1 |
| 15 | 72 |
| 16 | 224 |
| 17 | 168 |
| 18 | 128 |
| 19 | -1 |
| 20 | 180 |
| 21 | 192 |
| 22 | 390 |
| 23 | -1 |
| 24 | 240 |
| 25 | -1 |
| 26 | 972 |
| 27 | 360 |
| 28 | 384 |
| 29 | 420 |
| 30 | 432 |
| 31 | 480 |
| 32 | -1 |
| 33 | -1 |
| 34 | 720 |
| 35 | 1280 |
| 36 | 840 |
| 37 | 864 |
| 38 | -1 |
| 39 | 2112 |
| 40 | -1 |
| 41 | 1512 |
| 42 | 1152 |
| 43 | 1260 |
| 44 | -1 |
| 45 | 1440 |
| 46 | 3584 |
| 47 | 3120 |
| 48 | -1 |
| 49 | 2700 |
| 50 | 2688 |
| 51 | -1 |
| 52 | 3024 |
| 53 | -1 |
| 54 | 2310 |
| 55 | 3780 |
| 56 | 2592 |
[-1,3,4,6,8,12,-1,24,30,32,-1,48,60,-1,72,224,168, 128,-1,180,192,390,-1,240,-1,972,360,384,420,432, 480,-1,-1,720,1280,840,864,-1,2112,-1,1512,1152, 1260,-1,1440,3584,3120,-1,2700,2688,-1,3024,-1, 2310,3780,2592] |