A033032 Numbers all of whose base 6 digits are odd.

1, 3, 5, 7, 9, 11, 19, 21, 23, 31, 33, 35, 43, 45, 47, 55, 57, 59, 67, 69, 71, 115, 117, 119, 127, 129, 131, 139, 141, 143, 187, 189, 191, 199, 201, 203, 211, 213, 215, 259, 261, 263, 271, 273, 275, 283, 285, 287, 331, 333, 335, 343

Offset

1,2

Links

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

Formula

If (3^d-1)/2 <= n < (3^(d+1)-1)/2, then a(n+3^d) = a(n) + 6^n, a(n+2*3^d) = a(n) + 2*6^n, and a(n+3^(d+1)) = a(n) + 5*6^n. - Robert Israel, Aug 16 2018

Maple

g:= proc(t, d) local L;
    L:= convert(3^d+t, base, 3);
    add((2*L[i]+1)*6^(i-1), i=1..d);
end proc:
seq(seq(g(t, d), t=0..3^d-1), d=1..4); # Robert Israel, Aug 16 2018

Mathematica

Table[FromDigits[#, 6]&/@Tuples[{1, 3, 5}, n], {n, 4}]//Flatten (* Harvey P. Dale, Dec 24 2022 *)

Prog

(PARI) isok(n) = (n) && (#select(x->((x%2)==0), digits(n, 6)) == 0); \\ Michel Marcus, Aug 17 2018

Crossrefs

Sequence in context: A152484 A071643 A039578 * A103148 A211138 A178995

Adjacent sequences: A033029 A033030 A033031 * A033033 A033034 A033035

Keyword

nonn,base

Author

Clark Kimberling

Status

approved