A118731 -id:A118731 - 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

A118735 Numbers k such that 2^k and 3^k have odd digit sum.

Original entry on oeis.org

0, 4, 5, 10, 16, 18, 20, 22, 25, 27, 30, 31, 34, 35, 39, 48, 52, 53, 59, 62, 63, 66, 68, 69, 81, 87, 89, 92, 99, 100, 101, 105, 108, 114, 118, 119, 121, 127, 131, 133, 141, 145, 146, 150, 153, 158, 159, 160, 165, 167, 169, 175, 186, 188, 191, 196, 197, 201, 202, 203

Offset: 1

Zak Seidov, May 22 2006

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Cf. Intersection of A118731 and A118732.

Select[Range[0, 206], And @@ ((Mod[ Plus @@ IntegerDigits[ # ], 2] == 1 &) /@ {2^#, 3^#}) &] (* Ray Chandler, Jun 10 2006 *)
odsQ[n_]:=AllTrue[Total[IntegerDigits[#]]&/@{2^n,3^n},OddQ]; Select[ Range[ 0,250],odsQ] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jun 05 2021 *)

Extended by Ray Chandler, Jun 10 2006

cp's OEIS Frontend

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

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