A179803 Numbers that contain the digital reverse of their square root.

1, 25, 36, 729, 5476, 927369, 32752729, 37724164, 42562576, 97357689, 2825135104, 4325166756, 4860041796, 123715399824, 167904077121, 247679410276, 389724269841, 442094669604, 486004179600, 610118772201, 7473372660009, 15049783154025, 23983713798489, 25315841305225

Offset

1,2

Links

Giovanni Resta, Table of n, a(n) for n = 1..97 (terms < 1.6*10^25)

Formula

a(n) = A115761(n)^2.

Example

The square root of 729 is 27. 27's digital reverse is 72. 72 appears in 729.

Mathematica

fQ[n_] := StringPosition[ IntegerString[n^2], StringReverse@ IntegerString@ n] != {}; k = 1; lst = {}; While[k < 3879404, If[ fQ@k, AppendTo[lst, k^2]]; k++ ]; lst (* Robert G. Wilson v, Jul 28 2010 *)
drsrQ[n_]:=Module[{s=Sqrt[n]}, MemberQ[Partition[Reverse[ IntegerDigits[ n]], IntegerLength[ s], 1], IntegerDigits[s]]]; Select[Range[ 28*10^5]^2, drsrQ] (* Harvey P. Dale, Dec 15 2015 *)

Crossrefs

Cf. A115761.

Sequence in context: A030681 A167363 A035383 * A061863 A079270 A253025

Adjacent sequences: A179800 A179801 A179802 * A179804 A179805 A179806

Keyword

nonn,base

Author

Dominick Cancilla, Jul 27 2010

Extensions

More terms from Robert G. Wilson v, Jul 28 2010

Terms a(22) and beyond from Giovanni Resta, May 04 2020

Status

approved