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A006647 as a simple table
| n | a(n) |
|---|---|
| 4 | 1 |
| 5 | 1 |
| 6 | 3 |
| 7 | 6 |
| 8 | 15 |
| 9 | 33 |
| 10 | 83 |
| 11 | 202 |
| 12 | 527 |
| 13 | 1377 |
| 14 | 3744 |
| 15 | 10335 |
| 16 | 29297 |
| 17 | 84396 |
| 18 | 248034 |
| 19 | 740289 |
| 20 | 2245094 |
| 21 | 6904206 |
| 22 | 21522973 |
| 23 | 67936799 |
| 24 | 217026480 |
| 25 | 701159919 |
| 26 | 2289925258 |
| 27 | 7556363054 |
| 28 | 25184139149 |
| 29 | 84743377436 |
| 30 | 287815771822 |
| 31 | 986345040471 |
| 32 | 3409869008578 |
[1,1,3,6,15,33,83,202,527,1377,3744,10335,29297, 84396,248034,740289,2245094,6904206,21522973, 67936799,217026480,701159919,2289925258, 7556363054,25184139149,84743377436,287815771822, 986345040471,3409869008578] |