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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 4 |
| 3 | 4 |
| 4 | 22 |
| 5 | 65 |
| 6 | 193 |
| 7 | 628 |
| 8 | 1905 |
| 9 | 5929 |
| 10 | 18406 |
| 11 | 56934 |
| 12 | 176612 |
| 13 | 547378 |
| 14 | 1696245 |
| 15 | 5258441 |
| 16 | 16296976 |
| 17 | 50513593 |
| 18 | 156566213 |
| 19 | 485271504 |
| 20 | 1504098056 |
| 21 | 4661921212 |
| 22 | 14449556758 |
| 23 | 44786187665 |
| 24 | 138814082217 |
| 25 | 430252144356 |
| 26 | 1333559942209 |
| 27 | 4133348540461 |
[0,4,4,22,65,193,628,1905,5929,18406,56934,176612, 547378,1696245,5258441,16296976,50513593, 156566213,485271504,1504098056,4661921212, 14449556758,44786187665,138814082217,430252144356, 1333559942209,4133348540461] |