A074303 - OEIS

A074303

Sum of squares of digits of n is equal to the largest prime factor of n reversed, where the largest prime factor is not a palindrome.

%I #7 Dec 15 2017 17:36:01

%S 123,705,931,1230,1239,1521,2528,2812,4233,4665,6264,7050,7157,7316,

%T 8151,9310,11315,11745,12300,12390,13056,14104,14418,15192,15210,

%U 15281,16643,17444,17478,18827,20128,20953,21414,21437,23001,23275,24123

%N Sum of squares of digits of n is equal to the largest prime factor of n reversed, where the largest prime factor is not a palindrome.

%H Harvey P. Dale, <a href="/A074303/b074303.txt">Table of n, a(n) for n = 0..1000</a>

%e 1239 = 3.7.'59' and 1^2 + 2^2 + 3^2 + 9^2 = 95.

%t ssdQ[n_]:=Module[{lpf=FactorInteger[n][[-1,1]]},lpf!=IntegerReverse[lpf] && IntegerReverse[lpf]==Total[IntegerDigits[n]^2]]; Select[Range[ 25000], ssdQ] (* The program uses the IntegerReverse function from Mathematica version 10 *) (* _Harvey P. Dale_, Apr 11 2016 *)

%K base,nonn

%O 0,1

%A _Jason Earls_, Sep 21 2002