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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 4 |
| 3 | -1 |
| 4 | 10 |
| 5 | 3 |
| 6 | -1 |
| 7 | 14 |
| 8 | 8 |
| 9 | 18 |
| 10 | -1 |
| 11 | 28560 |
| 12 | 5 |
| 13 | 168 |
| 14 | 72 |
| 15 | -1 |
| 16 | 26 |
| 17 | 9 |
| 18 | 32 |
| 19 | 360 |
| 20 | 16068 |
| 21 | -1 |
| 22 | 25071688922457240 |
| 23 | 15 |
| 24 | 7 |
| 25 | 68 |
| 26 | 369465818568 |
| 27 | 1620 |
| 28 | -1 |
| 29 | 56 |
| 30 | 728 |
| 31 | 332 |
| 32 | 28398240 |
| 33 | 182 |
| 34 | 744768 |
| 35 | 1407318 |
| 36 | -1 |
| 37 | 170 |
| 38 | 11 |
| 39 | 161245807967271241368 |
| 40 | 98 |
| 41 | 248872305817685706212070112080 |
| 42 | 132 |
| 43 | 4175536688568 |
| 44 | 642 |
| 45 | -1 |
[2,4,-1,10,3,-1,14,8,18,-1,28560,5,168,72,-1,26,9, 32,360,16068,-1,25071688922457240,15,7,68, 369465818568,1620,-1,56,728,332,28398240,182, 744768,1407318,-1,170,11,161245807967271241368,98, 248872305817685706212070112080,132,4175536688568, 642,-1] |