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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 2 |
| 5 | 4 |
| 6 | 1 |
| 7 | 3 |
| 8 | 9 |
| 9 | 22 |
| 10 | 1 |
| 11 | 4 |
| 12 | 15 |
| 13 | 52 |
| 14 | 140 |
| 15 | 1 |
| 16 | 5 |
| 17 | 22 |
| 18 | 91 |
| 19 | 340 |
| 20 | 969 |
| 21 | 1 |
| 22 | 6 |
| 23 | 30 |
| 24 | 140 |
| 25 | 612 |
| 26 | 2394 |
| 27 | 7084 |
| 28 | 1 |
| 29 | 7 |
| 30 | 39 |
| 31 | 200 |
| 32 | 969 |
| 33 | 4389 |
| 34 | 17710 |
| 35 | 53820 |
| 36 | 1 |
| 37 | 8 |
| 38 | 49 |
| 39 | 272 |
| 40 | 1425 |
| 41 | 7084 |
| 42 | 32890 |
| 43 | 135720 |
| 44 | 420732 |
| 45 | 1 |
| 46 | 9 |
| 47 | 60 |
| 48 | 357 |
| 49 | 1995 |
| 50 | 10626 |
| 51 | 53820 |
| 52 | 254475 |
| 53 | 1068012 |
| 54 | 3362260 |
[1,1,1,1,2,4,1,3,9,22,1,4,15,52,140,1,5,22,91,340, 969,1,6,30,140,612,2394,7084,1,7,39,200,969,4389, 17710,53820,1,8,49,272,1425,7084,32890,135720, 420732,1,9,60,357,1995,10626,53820,254475,1068012, 3362260] |