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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 12 |
| 3 | 60 |
| 4 | 292 |
| 5 | 1292 |
| 6 | 5012 |
| 7 | 16628 |
| 8 | 49236 |
| 9 | 127964 |
| 10 | 285740 |
| 11 | 546308 |
| 12 | 902056 |
| 13 | 1298248 |
| 14 | 1639652 |
| 15 | 1841556 |
| 16 | 1841556 |
| 17 | 1639652 |
| 18 | 1298248 |
| 19 | 902056 |
| 20 | 546308 |
| 21 | 285740 |
| 22 | 127964 |
| 23 | 49236 |
| 24 | 16628 |
| 25 | 5012 |
| 26 | 1292 |
| 27 | 292 |
| 28 | 60 |
| 29 | 12 |
| 30 | 4 |
| 31 | 1 |
[1,4,12,60,292,1292,5012,16628,49236,127964, 285740,546308,902056,1298248,1639652,1841556, 1841556,1639652,1298248,902056,546308,285740, 127964,49236,16628,5012,1292,292,60,12,4,1] |