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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 7 |
| 3 | 20 |
| 4 | 57 |
| 5 | 157 |
| 6 | 432 |
| 7 | 1189 |
| 8 | 3270 |
| 9 | 8994 |
| 10 | 24735 |
| 11 | 68023 |
| 12 | 187064 |
| 13 | 514428 |
| 14 | 1414678 |
| 15 | 3890365 |
| 16 | 10698505 |
| 17 | 29420889 |
| 18 | 80907445 |
| 19 | 222495474 |
| 20 | 611862556 |
| 21 | 1682622029 |
| 22 | 4627210579 |
| 23 | 12724829094 |
| 24 | 34993280009 |
| 25 | 96231520027 |
| 26 | 264636680074 |
[1,2,7,20,57,157,432,1189,3270,8994,24735,68023, 187064,514428,1414678,3890365,10698505,29420889, 80907445,222495474,611862556,1682622029, 4627210579,12724829094,34993280009,96231520027, 264636680074] |