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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 4 |
| 5 | 9 |
| 6 | 20 |
| 7 | 48 |
| 8 | 115 |
| 9 | 286 |
| 10 | 718 |
| 11 | 1840 |
| 12 | 4761 |
| 13 | 12473 |
| 14 | 32938 |
| 15 | 87716 |
| 16 | 235119 |
| 17 | 634120 |
| 18 | 1719126 |
| 19 | 4682962 |
| 20 | 12810093 |
| 21 | 35176103 |
| 22 | 96925151 |
| 23 | 267912108 |
| 24 | 742665338 |
| 25 | 2064139687 |
| 26 | 5750927832 |
| 27 | 16058703976 |
| 28 | 44935017987 |
| 29 | 125978892299 |
| 30 | 353827590946 |
| 31 | 995440328858 |
[1,1,2,4,9,20,48,115,286,718,1840,4761,12473, 32938,87716,235119,634120,1719126,4682962, 12810093,35176103,96925151,267912108,742665338, 2064139687,5750927832,16058703976,44935017987, 125978892299,353827590946,995440328858] |