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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 12 |
| 4 | 47 |
| 5 | 170 |
| 6 | 750 |
| 7 | 3255 |
| 8 | 16010 |
| 9 | 81199 |
| 10 | 448156 |
| 11 | 2579626 |
| 12 | 15913058 |
| 13 | 102488024 |
| 14 | 698976419 |
| 15 | 4976098729 |
| 16 | 37195337408 |
| 17 | 289517846210 |
| 18 | 2352125666883 |
| 19 | 19841666995265 |
| 20 | 173888579505200 |
| 21 | 1577888354510786 |
| 22 | 14820132616197925 |
| 23 | 143746389756336173 |
| 24 | 1438846957477988926 |
[1,4,12,47,170,750,3255,16010,81199,448156, 2579626,15913058,102488024,698976419,4976098729, 37195337408,289517846210,2352125666883, 19841666995265,173888579505200,1577888354510786, 14820132616197925,143746389756336173, 1438846957477988926] |