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| n | a(n) |
|---|---|
| 2 | 4 |
| 3 | 17 |
| 4 | 72 |
| 5 | 329 |
| 6 | 473 |
| 7 | 1906 |
| 8 | 9067 |
| 9 | 40680 |
| 10 | 124068 |
| 11 | 340694 |
| 12 | 579517 |
| 13 | 2967748 |
| 14 | 9677489 |
| 15 | 36774905 |
| 16 | 85005719 |
| 17 | 350057197 |
| 18 | 673138588 |
| 19 | 3731385891 |
| 20 | 9039525037 |
| 21 | 40395250381 |
| 22 | 121209164997 |
| 23 | 412091649984 |
| 24 | 1293483111622 |
| 25 | 3934831116232 |
[4,17,72,329,473,1906,9067,40680,124068,340694, 579517,2967748,9677489,36774905,85005719, 350057197,673138588,3731385891,9039525037, 40395250381,121209164997,412091649984, 1293483111622,3934831116232] |