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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 8 |
| 2 | 52 |
| 3 | 308 |
| 4 | 1732 |
| 5 | 9428 |
| 6 | 50212 |
| 7 | 263348 |
| 8 | 1365892 |
| 9 | 7026068 |
| 10 | 35916772 |
| 11 | 182729588 |
| 12 | 926230852 |
| 13 | 4681485908 |
| 14 | 23608756132 |
| 15 | 118849087028 |
| 16 | 597466660612 |
| 17 | 3000218204948 |
| 18 | 15052630632292 |
| 19 | 75469311591668 |
| 20 | 378171191679172 |
| 21 | 1894154493279188 |
| 22 | 9483966605929252 |
[1,8,52,308,1732,9428,50212,263348,1365892, 7026068,35916772,182729588,926230852,4681485908, 23608756132,118849087028,597466660612, 3000218204948,15052630632292,75469311591668, 378171191679172,1894154493279188,9483966605929252] |