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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 4 |
| 3 | 13 |
| 4 | 80 |
| 5 | 401 |
| 6 | 1924 |
| 7 | 9773 |
| 8 | 48960 |
| 9 | 243841 |
| 10 | 1220644 |
| 11 | 6105133 |
| 12 | 30514640 |
| 13 | 152585681 |
| 14 | 762958564 |
| 15 | 3814670093 |
| 16 | 19073445120 |
| 17 | 95367649921 |
| 18 | 476836927684 |
| 19 | 2384185160653 |
| 20 | 11920931368400 |
| 21 | 59604643100561 |
| 22 | 298023215160004 |
| 23 | 1490116145192813 |
| 24 | 7450580588892480 |
| 25 | 37252902871641601 |
| 26 | 186264515189207524 |
[0,1,4,13,80,401,1924,9773,48960,243841,1220644, 6105133,30514640,152585681,762958564,3814670093, 19073445120,95367649921,476836927684, 2384185160653,11920931368400,59604643100561, 298023215160004,1490116145192813,7450580588892480, 37252902871641601,186264515189207524] |