A118730 - OEIS

%I #7 Apr 12 2021 17:48:10

%S 1,2,3,6,9,11,13,14,15,17,21,26,32,33,36,37,41,42,43,44,45,46,47,50,

%T 51,54,55,57,58,60,61,64,65,67,70,71,73,74,76,77,78,79,80,82,83,84,85,

%U 86,90,91,95,98,102,103,106,107,112,113,115,116,117,120,122,123,124,126

%N Numbers n such that 2^n has even digit sum.

%H Robert Israel, <a href="/A118730/b118730.txt">Table of n, a(n) for n = 1..10000</a>

%p filter:= proc(n) convert(convert(2^n,base,10),`+`)::even end proc:

%p select(filter, [$1..1000]); # _Robert Israel_, Apr 12 2021

%t Select[Range[126], Mod[ Plus @@ IntegerDigits[2^# ], 2] == 0 &] (* _Ray Chandler_, Jun 10 2006 *)

%Y Cf. A118733, A118734.

%K base,nonn

%O 1,2

%A _Zak Seidov_, May 22 2006