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A175396 Numbers n such that the sum of the squares of its digits is a perfect square. 7

%I

%S 0,1,2,3,4,5,6,7,8,9,10,20,30,34,40,43,50,60,68,70,80,86,90,100,122,

%T 148,184,200,212,221,236,244,263,269,296,300,304,326,340,362,366,400,

%U 403,418,424,430,442,447,474,481,488,500,600,608,623,629,632,636,663

%N Numbers n such that the sum of the squares of its digits is a perfect square.

%C Previous name was: Numbers n such that Sum_{i=1..r, x(i)^2} is a perfect square, where x(i) = digits of n. r=1+floor(log_10 n).

%H Christian N. K. Anderson, <a href="/A175396/b175396.txt">Table of n, a(n) for n = 1..10000</a>

%e n=34, 3*3+4*4=25 is a perfect square so n=34 belongs to the sequence. n=122, 1*1+2*2+2*2=9 is a perfect square so n=122 belongs to the sequence.

%t Select[Range[0, 666], IntegerQ[Sqrt[Plus @@ (IntegerDigits[#]^2)]] &] (* _Ivan Neretin_, Aug 03 2015 *)

%o (PARI) isok(n) = {digs = Vec(Str(n)); issquare(sum(i=1, #digs, eval(digs[i])^2))} \\ _Michel Marcus_, Jun 02 2013

%Y Cf. A084561.

%K base,easy,nonn

%O 1,3

%A _Ctibor O. Zizka_, Apr 30 2010

%E Corrected and extended by Neven Juric, Jul 12 2010

%E Simpler definition by _Michel Marcus_, Jun 02 2013

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Last modified August 12 21:10 EDT 2020. Contains 336440 sequences. (Running on oeis4.)