|
%I #15 May 04 2020 14:28:17
%S 1,25,36,729,5476,927369,32752729,37724164,42562576,97357689,
%T 2825135104,4325166756,4860041796,123715399824,167904077121,
%U 247679410276,389724269841,442094669604,486004179600,610118772201,7473372660009,15049783154025,23983713798489,25315841305225
%N Numbers that contain the digital reverse of their square root.
%H Giovanni Resta, <a href="/A179803/b179803.txt">Table of n, a(n) for n = 1..97</a> (terms < 1.6*10^25)
%F a(n) = A115761(n)^2.
%e The square root of 729 is 27. 27's digital reverse is 72. 72 appears in 729.
%t 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 *)
%t 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 *)
%Y Cf. A115761.
%K nonn,base
%O 1,2
%A _Dominick Cancilla_, Jul 27 2010
%E More terms from _Robert G. Wilson v_, Jul 28 2010
%E Terms a(22) and beyond from _Giovanni Resta_, May 04 2020
|
