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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 7 |
| 4 | 23 |
| 5 | 68 |
| 6 | 194 |
| 7 | 555 |
| 8 | 1601 |
| 9 | 4633 |
| 10 | 13404 |
| 11 | 38752 |
| 12 | 112004 |
| 13 | 323728 |
| 14 | 935737 |
| 15 | 2704817 |
| 16 | 7818464 |
| 17 | 22599701 |
| 18 | 65325542 |
| 19 | 188826693 |
| 20 | 545813094 |
| 21 | 1577700612 |
| 22 | 4560424135 |
| 23 | 13182138184 |
| 24 | 38103641048 |
| 25 | 110140512968 |
| 26 | 318366757185 |
| 27 | 920255312908 |
| 28 | 2660044812499 |
| 29 | 7688994894381 |
[1,1,2,7,23,68,194,555,1601,4633,13404,38752, 112004,323728,935737,2704817,7818464,22599701, 65325542,188826693,545813094,1577700612, 4560424135,13182138184,38103641048,110140512968, 318366757185,920255312908,2660044812499, 7688994894381] |