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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 18 |
| 5 | 1 |
| 6 | 1 |
| 7 | 90 |
| 8 | 90 |
| 9 | 1 |
| 10 | 1 |
| 11 | 280 |
| 12 | 1400 |
| 13 | 280 |
| 14 | 1 |
| 15 | 1 |
| 16 | 675 |
| 17 | 10500 |
| 18 | 10500 |
| 19 | 675 |
| 20 | 1 |
| 21 | 1 |
| 22 | 1386 |
| 23 | 51975 |
| 24 | 161700 |
| 25 | 51975 |
| 26 | 1386 |
| 27 | 1 |
| 28 | 1 |
| 29 | 2548 |
| 30 | 196196 |
| 31 | 1471470 |
| 32 | 1471470 |
| 33 | 196196 |
| 34 | 2548 |
| 35 | 1 |
| 36 | 1 |
| 37 | 4320 |
| 38 | 611520 |
| 39 | 9417408 |
| 40 | 22702680 |
| 41 | 9417408 |
| 42 | 611520 |
| 43 | 4320 |
| 44 | 1 |
| 45 | 1 |
| 46 | 6885 |
| 47 | 1652400 |
| 48 | 46781280 |
| 49 | 231567336 |
| 50 | 231567336 |
| 51 | 46781280 |
| 52 | 1652400 |
| 53 | 6885 |
| 54 | 1 |
[1,1,1,1,18,1,1,90,90,1,1,280,1400,280,1,1,675, 10500,10500,675,1,1,1386,51975,161700,51975,1386, 1,1,2548,196196,1471470,1471470,196196,2548,1,1, 4320,611520,9417408,22702680,9417408,611520,4320, 1,1,6885,1652400,46781280,231567336,231567336, 46781280,1652400,6885,1] |