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A167039 Squares that remain squares when prefixed with a 5. 3
625, 62500, 6250000, 58140625, 625000000, 5814062500, 6703515625, 62500000000, 581406250000, 670351562500, 6250000000000, 58140625000000, 67035156250000, 539545791015625, 625000000000000, 5814062500000000, 6703515625000000, 53954579101562500 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Numbers s of A000290 such that 5*10^A055642(s)+s is also in A000290.

LINKS

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

EXAMPLE

625 = 25^2 is a square and becomes the square 5625 = 75^2 if a 5 is attached in front of its decimal representation.

MAPLE

P:=proc(i) local a, n; for n from 1 by 1 to i do a:=5*10^floor(1+log10(n^2))+n^2; if a=trunc(sqrt(a))^2 then print(n^2); fi; od; end: P(1000000000000); # Paolo P. Lava, Nov 02 2009

CROSSREFS

Sequence in context: A017224 A106321 A017332 * A265932 A017452 A223230

Adjacent sequences:  A167036 A167037 A167038 * A167040 A167041 A167042

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

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Last modified October 18 01:39 EDT 2021. Contains 348065 sequences. (Running on oeis4.)