A053909 Squares composed of digits {1,6,8}.

1, 16, 81, 1681, 11881, 1666681, 818188816, 6168688681, 6661661161, 611686666816, 1111166866161, 11168168618161, 18886681666161, 666868181611681, 866686868686116, 16668111611611681, 668881818661618116, 866881188818186116, 6181118111681186116, 6811866166886681616

Offset: 1

Author

Patrick De Geest, Mar 15 2000

Keywords

• nonn
• base

Links

• Andrew Howroyd, Table of n, a(n) for n = 1..27
• P. De Geest, Squares containing at most three distinct digits, Index entries for related sequences

Crossrefs

Cf. A053908.

Programs

Mathematica

Flatten[Table[Select[FromDigits/@Tuples[{1,6,8},{n}], IntegerQ[Sqrt[#]]&],{n,10}]]  (* Harvey P. Dale, Apr 22 2011 *)

Formula

a(n) = A053908(n)^2. - Andrew Howroyd, Oct 18 2024

Extensions

a(18) onwards using A053908 added by Andrew Howroyd, Oct 18 2024