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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 5 |
| 3 | 12 |
| 4 | 51 |
| 5 | 172 |
| 6 | 624 |
| 7 | 2216 |
| 8 | 7970 |
| 9 | 28660 |
| 10 | 103599 |
| 11 | 375854 |
| 12 | 1368883 |
| 13 | 5003340 |
| 14 | 18351050 |
| 15 | 67525962 |
| 16 | 249235562 |
| 17 | 922567826 |
| 18 | 3424217898 |
| 19 | 12741735980 |
| 20 | 47526320684 |
| 21 | 177671217830 |
| 22 | 665611279282 |
| 23 | 2498575823284 |
| 24 | 9396889413586 |
[0,5,12,51,172,624,2216,7970,28660,103599,375854, 1368883,5003340,18351050,67525962,249235562, 922567826,3424217898,12741735980,47526320684, 177671217830,665611279282,2498575823284, 9396889413586] |