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A035122 Roots of 'squares remaining square when written backwards'. 0
1, 2, 3, 11, 12, 13, 21, 22, 26, 31, 33, 99, 101, 102, 103, 111, 112, 113, 121, 122, 201, 202, 211, 212, 221, 264, 301, 307, 311, 836, 1001, 1002, 1003, 1011, 1012, 1013, 1021, 1022, 1031, 1101, 1102, 1103, 1111, 1112, 1113, 1121, 1122, 1201, 1202, 1211 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Numbers with trailing zeros are excluded.

LINKS

Table of n, a(n) for n=1..50.

Eric Weisstein's World of Mathematics, Square Number

Index entry for sequences related to reversing digits of squares

FORMULA

a(n) = sqrt(A033294(n)). - Michel Marcus, Sep 22 2015

EXAMPLE

E.g., 99^2 = 9801 -> 1089 = 33^2.

MATHEMATICA

Select[Range[10000], IntegerQ[Sqrt[FromDigits[Reverse[IntegerDigits[ #^2]]]]] &] (* and then delete terms ending with 0 - N. J. A. Sloane, Jul 08 2011 *)

Sqrt[Select[Range[2000]^2, Mod[#, 10]!=0&&IntegerQ[Sqrt[FromDigits[Reverse[IntegerDigits[#]]]]]&]] (* Vincenzo Librandi, Sep 22 2015 *)

CROSSREFS

Cf. A033294, A035125.

Sequence in context: A130803 A007932 A334054 * A085305 A189818 A116032

Adjacent sequences:  A035119 A035120 A035121 * A035123 A035124 A035125

KEYWORD

nonn,base

AUTHOR

Patrick De Geest, Nov 15 1998

STATUS

approved

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Last modified May 8 18:28 EDT 2021. Contains 343666 sequences. (Running on oeis4.)