A118730 Numbers k such that 2^k has even digit sum.

1, 2, 3, 6, 9, 11, 13, 14, 15, 17, 21, 26, 32, 33, 36, 37, 41, 42, 43, 44, 45, 46, 47, 50, 51, 54, 55, 57, 58, 60, 61, 64, 65, 67, 70, 71, 73, 74, 76, 77, 78, 79, 80, 82, 83, 84, 85, 86, 90, 91, 95, 98, 102, 103, 106, 107, 112, 113, 115, 116, 117, 120, 122, 123, 124, 126

Offset: 1

Author

Zak Seidov, May 22 2006

Keywords

• nonn
• base

Links

• Robert Israel, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A118733, A118734.

Programs

Maple

filter:= proc(n) convert(convert(2^n,base,10),`+`)::even end proc:
select(filter, [$1..1000]); # Robert Israel, Apr 12 2021

Mathematica

Select[Range[126], Mod[ Plus @@ IntegerDigits[2^# ], 2] == 0 &] (* Ray Chandler, Jun 10 2006 *)