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

Author

Dominick Cancilla, Jul 27 2010

Keywords

• nonn
• base

Examples

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

Links

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

Crossrefs

Cf. A115761.

Programs

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 *)

Formula

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

Extensions

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

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