A118735 -id:A118735 - cp's OEIS frontend

A118732 Numbers k such that 3^k has odd digit sum.

0, 1, 2, 3, 4, 5, 9, 10, 11, 13, 14, 16, 17, 18, 20, 21, 22, 25, 26, 27, 30, 31, 32, 34, 35, 36, 39, 41, 45, 48, 51, 52, 53, 59, 60, 61, 62, 63, 65, 66, 68, 69, 73, 74, 76, 78, 79, 80, 81, 86, 87, 89, 91, 92, 98, 99, 100, 101, 103, 105, 108, 113, 114, 115, 117, 118, 119, 121

Offset: 1

Zak Seidov, May 22 2006

Numbers k such that A000244(k) is in A054684. - Robert Israel, Jun 28 2017

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

Cf. A000244, A054684, A118731, A118735.

select(t -> convert(convert(3^t,base,10),`+`)::odd, [$0..1000]); # Robert Israel, Jun 28 2017

Select[Range[0, 121], Mod[ Plus @@ IntegerDigits[3^# ], 2] == 1 &] (* Ray Chandler, Jun 10 2006 *)
Select[Range[0,200],OddQ[Total[IntegerDigits[3^#]]]&] (* Harvey P. Dale, Dec 30 2021 *)

isok(n) = (sumdigits(3^n) % 2) == 1; \\ Michel Marcus, Jun 28 2017

A118731 Numbers k such that 2^k has odd digit sum.

Original entry on oeis.org

0, 4, 5, 7, 8, 10, 12, 16, 18, 19, 20, 22, 23, 24, 25, 27, 28, 29, 30, 31, 34, 35, 38, 39, 40, 48, 49, 52, 53, 56, 59, 62, 63, 66, 68, 69, 72, 75, 81, 87, 88, 89, 92, 93, 94, 96, 97, 99, 100, 101, 104, 105, 108, 109, 110, 111, 114, 118, 119, 121, 125, 127, 131, 132, 133

Offset: 1

Zak Seidov, May 22 2006

Cf. A118732, A118735, A076203.

Select[Range[0, 133], Mod[ Plus @@ IntegerDigits[2^# ], 2] == 1 &] (* Ray Chandler, Jun 10 2006 *)

cp's OEIS Frontend

A118732 Numbers k such that 3^k has odd digit sum.

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