A053893 Squares composed of digits {1,3,6}.

1, 16, 36, 361, 3136, 136161, 633616, 1313316, 1336336, 13366336, 66113161, 363131136, 1616361616, 6661661161, 66631613161, 31633661633161, 613163131661161, 131616316361116161, 1166361161363316361, 136113161636611666116, 316661133333361663161316, 11136331666361661633111616

Offset: 1

Author

Patrick De Geest, Mar 15 2000

Keywords

• nonn
• base

Links

• Zhao Hui Du, Table of n, a(n) for n = 1..25
• Patrick De Geest, Squares containing at most three distinct digits, Index entries for related sequences.
• Hisanori Mishima, Sporadic tridigital solutions.

Crossrefs

Cf. A053892.

Programs

Mathematica

Select[Flatten[Table[FromDigits/@Tuples[{1,3,6},n],{n,20}]],IntegerQ[ Sqrt[ #]]&] (* Harvey P. Dale, Jul 20 2021 *)

Formula

a(n) = A053892(n)^2. - Elmo R. Oliveira, Jul 16 2025

Extensions

More terms from C. Ronaldo (aga_new_ac(AT)hotmail.com), Jan 04 2005