A167038 Squares that remain squares when prefixed with a 4.

9, 225, 900, 2025, 22500, 90000, 202500, 950625, 2250000, 9000000, 20250000, 85100625, 95062500, 225000000, 900000000, 2025000000, 2487515625, 8510062500, 9506250000, 18123890625, 22500000000, 90000000000, 202500000000, 248751562500, 851006250000

Offset: 1

Author

Claudio Meller, Oct 27 2009

Keywords

• nonn
• base

Examples

			9 = 3^2 is a square and becomes the square 49 = 7^2 if a 4 is attached in front of its decimal representation.
		

Links

• Chai Wah Wu, Table of n, a(n) for n = 1..1000

Programs

Mathematica

Select[Range[450000]^2,IntegerQ[Sqrt[FromDigits[Join[{4}, IntegerDigits[ #]]]]]&] (* Harvey P. Dale, Aug 05 2014 *)

Extensions

Keyword:base added by R. J. Mathar, Oct 28 2009

More terms from Chai Wah Wu, Sep 11 2014