A119496 - OEIS

%I #7 Oct 13 2022 10:51:58

%S 15,64,83,90,106,107,120,122,135,168,173,180,181,185,193,198,222,229,

%T 239,242,289,299,347,356,364,369,407,424,447,458,462,470,479,481,503,

%U 542,552,568,580,583,607,612,648,657,676,683,684,688,742,758,787

%N Numbers n such that 2^n, 3^n, 5^n and 7^n have even digit sum.

%e {2^15,3^15,5^15,7^15}={32768,14348907,30517578125,4747561509943} with even digit sum {26,36,44,64}.

%t Select[Range[800],AllTrue[Total/@(IntegerDigits/@({2,3,5,7}^#)),EvenQ]&] (* _Harvey P. Dale_, Oct 13 2022 *)

%o (PARI) isok(n) = !(sumdigits(2^n) % 2) && !(sumdigits(3^n) % 2) && !(sumdigits(5^n) % 2) && !(sumdigits(7^n) % 2); \\ _Michel Marcus_, Oct 10 2013

%Y Subsequence of A118734 and of A118867.

%K base,nonn

%O 1,1

%A _Zak Seidov_, May 26 2006