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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 12 |
| 3 | 54 |
| 4 | 247 |
| 5 | 1157 |
| 6 | 5525 |
| 7 | 26580 |
| 8 | 128853 |
| 9 | 628206 |
| 10 | 3074634 |
| 11 | 15098654 |
| 12 | 74332605 |
| 13 | 366717536 |
| 14 | 1812346379 |
| 15 | 8969290288 |
| 16 | 44442880247 |
| 17 | 220439573132 |
| 18 | 1094337080001 |
| 19 | 5436755934137 |
| 20 | 27027748564962 |
| 21 | 134438825514054 |
| 22 | 669044373417219 |
| 23 | 3330995247406229 |
| 24 | 16590531257530794 |
| 25 | 82659922500408035 |
[1,3,12,54,247,1157,5525,26580,128853,628206, 3074634,15098654,74332605,366717536,1812346379, 8969290288,44442880247,220439573132,1094337080001, 5436755934137,27027748564962,134438825514054, 669044373417219,3330995247406229, 16590531257530794,82659922500408035] |