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A167038
Squares that remain squares when prefixed with a 4.
3
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
1,1
EXAMPLE
9 = 3^2 is a square and becomes the square 49 = 7^2 if a 4 is attached in front of its decimal representation.
MATHEMATICA
Select[Range[450000]^2, IntegerQ[Sqrt[FromDigits[Join[{4}, IntegerDigits[ #]]]]]&] (* Harvey P. Dale, Aug 05 2014 *)
CROSSREFS
Sequence in context: A014736 A017558 A159939 * A074190 A069075 A218659
KEYWORD
nonn,base
AUTHOR
Claudio Meller, Oct 27 2009
EXTENSIONS
Keyword:base added by R. J. Mathar, Oct 28 2009
More terms from Chai Wah Wu, Sep 11 2014
STATUS
approved