A077676 Squares using only squarefree digits (2, 3, 5, 6, 7).

25, 36, 225, 256, 576, 625, 676, 5625, 5776, 7225, 27225, 27556, 37636, 55225, 65536, 75625, 225625, 226576, 235225, 265225, 266256, 275625, 276676, 367236, 525625, 553536, 732736, 765625, 767376, 2322576, 2325625, 2356225, 2637376, 2673225

Offset: 1

Author

Amarnath Murthy, Nov 16 2002

Keywords

• base
• nonn

Comments

a(n) is == 5 or 6 (mod 10).

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..600

Crossrefs

Cf. A077674, A077675, A006716. Different from A077437.

Programs

Mathematica

sfdsQ[n_]:=Module[{idn=DigitCount[n]},idn[[1]]==idn[[4]]==idn[[8]] == idn[[9]]==idn[[10]]==0]; Select[Range[2000]^2,sfdsQ] (* Harvey P. Dale, Oct 09 2011 *)
Table[Select[FromDigits/@Tuples[{2,3,5,6,7},n],IntegerQ[Sqrt[#]]&],{n,2,7}]//Flatten (* Harvey P. Dale, Feb 04 2015 *)

Extensions

Corrected and extended by Sascha Kurz, Jan 28 2003