A037862 a(n)=(number of digits <=1)-(number of digits >1) in base 3 representation of n.

1, -1, 2, 2, 0, 0, 0, -2, 3, 3, 1, 3, 3, 1, 1, 1, -1, 1, 1, -1, 1, 1, -1, -1, -1, -3, 4, 4, 2, 4, 4, 2, 2, 2, 0, 4, 4, 2, 4, 4, 2, 2, 2, 0, 2, 2, 0, 2, 2, 0, 0, 0, -2, 2, 2, 0, 2, 2, 0, 0, 0, -2, 2, 2, 0, 2, 2, 0, 0, 0, -2, 0, 0, -2, 0, 0, -2, -2, -2, -4, 5, 5, 3

Offset: 1

Author

Clark Kimberling

Keywords

• base
• sign

Crossrefs

Cf. A081604, A081603.

Programs

Maple

A037862 := proc(n)
    a := 0 ;
    dgs := convert(n,base,3);
    for i from 1 to nops(dgs) do
        if op(i,dgs)<=1 then
            a := a+1 ;
        else
            a := a-1 ;
        end if;
    end do:
    a ;
end proc: # R. J. Mathar, Oct 16 2015

Mathematica

b3d[n_]:=Module[{idn=IntegerDigits[n,3]},Count[idn,?(#<2&)]-Count[idn, ?(#>1&)]]; Array[b3d,90] (* Harvey P. Dale, Nov 08 2011 *)

Formula

a(n) = A081604(n)-2*A081603(n). - R. J. Mathar, Jan 27 2025