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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 4 |
| 3 | 15 |
| 4 | 44 |
| 5 | 120 |
| 6 | 319 |
| 7 | 804 |
| 8 | 1960 |
| 9 | 4652 |
| 10 | 10782 |
| 11 | 24435 |
| 12 | 54329 |
| 13 | 118663 |
| 14 | 254969 |
| 15 | 539825 |
| 16 | 1127247 |
| 17 | 2323811 |
| 18 | 4733634 |
| 19 | 9535025 |
| 20 | 19005218 |
| 21 | 37507726 |
| 22 | 73333405 |
| 23 | 142112298 |
| 24 | 273092198 |
| 25 | 520612163 |
| 26 | 984943887 |
| 27 | 1849920530 |
| 28 | 3450475858 |
| 29 | 6393203485 |
| 30 | 11770416017 |
| 31 | 21538245911 |
| 32 | 39181212114 |
[0,1,4,15,44,120,319,804,1960,4652,10782,24435, 54329,118663,254969,539825,1127247,2323811, 4733634,9535025,19005218,37507726,73333405, 142112298,273092198,520612163,984943887, 1849920530,3450475858,6393203485,11770416017, 21538245911,39181212114] |