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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 8 |
| 3 | 60 |
| 4 | 464 |
| 5 | 3734 |
| 6 | 30484 |
| 7 | 252154 |
| 8 | 2105064 |
| 9 | 17701326 |
| 10 | 149708146 |
| 11 | 1272108368 |
| 12 | 10851700690 |
| 13 | 92875809416 |
| 14 | 797134845184 |
| 15 | 6858361265978 |
| 16 | 59133629878796 |
| 17 | 510815878314050 |
| 18 | 4419961056157870 |
| 19 | 38301854208088068 |
| 20 | 332355738077962284 |
[1,8,60,464,3734,30484,252154,2105064,17701326, 149708146,1272108368,10851700690,92875809416, 797134845184,6858361265978,59133629878796, 510815878314050,4419961056157870, 38301854208088068,332355738077962284] |