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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 2 |
| 2 | 7 |
| 3 | 28 |
| 4 | 116 |
| 5 | 480 |
| 6 | 1968 |
| 7 | 8000 |
| 8 | 32320 |
| 9 | 130048 |
| 10 | 521984 |
| 11 | 2092032 |
| 12 | 8377344 |
| 13 | 33529856 |
| 14 | 134164480 |
| 15 | 536756224 |
| 16 | 2147237888 |
| 17 | 8589410304 |
| 18 | 34358624256 |
| 19 | 137436594176 |
| 20 | 549750833152 |
| 21 | 2199012769792 |
| 22 | 8796071002112 |
| 23 | 35184325951488 |
| 24 | 140737391886336 |
| 25 | 562949752094720 |
[0,2,7,28,116,480,1968,8000,32320,130048,521984, 2092032,8377344,33529856,134164480,536756224, 2147237888,8589410304,34358624256,137436594176, 549750833152,2199012769792,8796071002112, 35184325951488,140737391886336,562949752094720] |