A118733 Numbers k such that 3^k has even digit sum.

6, 7, 8, 12, 15, 19, 23, 24, 28, 29, 33, 37, 38, 40, 42, 43, 44, 46, 47, 49, 50, 54, 55, 56, 57, 58, 64, 67, 70, 71, 72, 75, 77, 82, 83, 84, 85, 88, 90, 93, 94, 95, 96, 97, 102, 104, 106, 107, 109, 110, 111, 112, 116, 120, 122, 125, 126, 129, 132, 135, 136, 138, 139

Offset

1,1

Links

Clinton Walker, Table of n, a(n) for n = 1..10000

Mathematica

Select[Range[140], Mod[ Plus @@ IntegerDigits[3^# ], 2] == 0 &] (* Ray Chandler, Jun 10 2006 *)
Select[Range[150], EvenQ[Total[IntegerDigits[3^#]]]&] (* Harvey P. Dale, Mar 12 2013 *)

Prog

(Python)
from gmpy2 import digits
def ok(n): return sum(map(int, digits(3**n)))&1 == 0
print([k for k in range(140) if ok(k)]) # Michael S. Branicky, May 11 2025

Crossrefs

Cf. A004166, A118730, A118734.

Sequence in context: A066235 A037365 A083340 * A328118 A047275 A373385

Adjacent sequences: A118730 A118731 A118732 * A118734 A118735 A118736

Keyword

nonn,base

Author

Zak Seidov, May 22 2006

Status

approved