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| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 16 |
| 3 | 64 |
| 4 | 232 |
| 5 | 696 |
| 6 | 2072 |
| 7 | 6130 |
| 8 | 18378 |
| 9 | 55716 |
| 10 | 169734 |
| 11 | 517764 |
| 12 | 1578184 |
| 13 | 4806344 |
| 14 | 14629384 |
| 15 | 44519552 |
| 16 | 135480532 |
| 17 | 412314438 |
| 18 | 1254882280 |
| 19 | 3819338704 |
| 20 | 11624541548 |
| 21 | 35380360780 |
| 22 | 107682931160 |
| 23 | 327740673246 |
| 24 | 997501106370 |
| 25 | 3035962621026 |
[4,16,64,232,696,2072,6130,18378,55716,169734, 517764,1578184,4806344,14629384,44519552, 135480532,412314438,1254882280,3819338704, 11624541548,35380360780,107682931160,327740673246, 997501106370,3035962621026] |