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| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 16 |
| 3 | 48 |
| 4 | 248 |
| 5 | 1024 |
| 6 | 3968 |
| 7 | 15872 |
| 8 | 65536 |
| 9 | 262144 |
| 10 | 1048576 |
| 11 | 4177632 |
| 12 | 16777216 |
| 13 | 67108864 |
| 14 | 268435456 |
| 15 | 1073479680 |
| 16 | 4294961152 |
| 17 | 17179869184 |
| 18 | 68719378432 |
| 19 | 274872664064 |
| 20 | 1099511627776 |
| 21 | 4398046511104 |
| 22 | 17592186044416 |
| 23 | 70368641459200 |
[4,16,48,248,1024,3968,15872,65536,262144,1048576, 4177632,16777216,67108864,268435456,1073479680, 4294961152,17179869184,68719378432,274872664064, 1099511627776,4398046511104,17592186044416, 70368641459200] |