A117676 - OEIS

%I #6 Feb 14 2016 17:44:08

%S 0,1,4,9,36,49,64,81,100,121,144,225,256,289,324,361,400,441,576,625,

%T 676,729,784,841,900,1089,1156,1225,1296,1369,1444,1521,1764,1849,

%U 1936,2025,2116,2209,2304,2601,2704,2809,2916,3025,3136,3249,3600,3721,3844

%N Squares for which the digital root is also a square.

%H Harvey P. Dale, <a href="/A117676/b117676.txt">Table of n, a(n) for n = 0..10000</a>

%F Empirical g.f.: -x*(x +1)*(x^12 +2*x^11 +3*x^10 +24*x^9 -11*x^8 +26*x^7 -9*x^6 +26*x^5 -11*x^4 +24*x^3 +3*x^2 +2*x +1) / ((x -1)^3*(x^6 +x^5 +x^4 +x^3 +x^2 +x +1)^2). - _Colin Barker_, Jan 17 2014

%t drQ[n_]:=IntegerQ[Sqrt[NestWhile[Total[IntegerDigits[#]]&,n,#>9&]]]; Select[Range[0,100]^2,drQ] (* _Harvey P. Dale_, Feb 14 2016 *)

%Y Cf. A000290.

%K nonn,base

%O 0,3

%A Luc Stevens (lms022(AT)yahoo.com), Apr 12 2006