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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 15 |
| 3 | 124 |
| 4 | 603 |
| 5 | 2173 |
| 6 | 6204 |
| 7 | 15201 |
| 8 | 33149 |
| 9 | 66002 |
| 10 | 122410 |
| 11 | 214186 |
| 12 | 357189 |
| 13 | 572385 |
| 14 | 886117 |
| 15 | 1330930 |
| 16 | 1947746 |
| 17 | 2787431 |
| 18 | 3907866 |
| 19 | 5380602 |
| 20 | 7288597 |
| 21 | 9729060 |
| 22 | 12815704 |
| 23 | 16677303 |
| 24 | 21461500 |
| 25 | 27340308 |
| 26 | 34501149 |
| 27 | 43160975 |
| 28 | 53560487 |
| 29 | 65967718 |
| 30 | 80677972 |
| 31 | 98029728 |
[0,1,15,124,603,2173,6204,15201,33149,66002, 122410,214186,357189,572385,886117,1330930, 1947746,2787431,3907866,5380602,7288597,9729060, 12815704,16677303,21461500,27340308,34501149, 43160975,53560487,65967718,80677972,98029728] |