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A083978 as a simple table

na(n)
17
2727
372727
477377
51777771
67772777
717772727771
8777767777
972777777727
1077777677777
117767777777677
127777774777777
13377777777777773
14777777727777777
1572777777777777727
1677777777677777777
177776777777777776777
18717777777787777777717
19737777777777777777737

[7,727,72727,77377,1777771,7772777,17772727771,
 777767777,72777777727,77777677777,7767777777677,
 7777774777777,377777777777773,777777727777777,
 72777777777777727,77777777677777777,
 7776777777777776777,717777777787777777717,
 737777777777777777737]