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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 7 |
| 2 | 47 |
| 3 | 327 |
| 4 | 2343 |
| 5 | 17127 |
| 6 | 126951 |
| 7 | 950631 |
| 8 | 7173991 |
| 9 | 54471527 |
| 10 | 415652711 |
| 11 | 3184708455 |
| 12 | 24485137255 |
| 13 | 188802730855 |
| 14 | 1459525454695 |
| 15 | 11307626564455 |
| 16 | 87775235181415 |
| 17 | 682523302202215 |
| 18 | 5315297718995815 |
| 19 | 41450938169985895 |
| 20 | 323653082644384615 |
| 21 | 2529960757626047335 |
[1,7,47,327,2343,17127,126951,950631,7173991, 54471527,415652711,3184708455,24485137255, 188802730855,1459525454695,11307626564455, 87775235181415,682523302202215,5315297718995815, 41450938169985895,323653082644384615, 2529960757626047335] |