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A053973

Squares composed of digits {6,7,9}.

9, 676, 69696, 97969, 9696996, 9697699776769, 77797697969777769, 776797677679677696, 6776696769676669969, 9767769967769766976, 97667999767779769677969, 7676999976999997667777796, 69997676676669667699797969, 67976976676979976697777676769, 96667776776767999797799699976676

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OFFSET

1,1

LINKS

Table of n, a(n) for n=1..15.

P. De Geest, Squares containing at most three distinct digits, Index entries for related sequences

Author?, Source (txt)

Hisanori Mishima, Sporadic tridigital solutions

FORMULA

a(n) = A053972(n)^2.

MATHEMATICA

Flatten[Table[Select[FromDigits/@Tuples[{6, 7, 9}, i], IntegerQ[Sqrt[#]]&], {i, 23}]] (* Harvey P. Dale, Dec 07 2014 *)