A037862 - OEIS

%I #9 Oct 16 2015 16:28:00

%S 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,

%T 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,

%U 2,0,2,2,0,0,0,-2,0,0,-2,0,0,-2,-2,-2,-4,5,5,3

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

%p A037862 := proc(n)

%p     a := 0 ;

%p     dgs := convert(n,base,3);

%p     for i from 1 to nops(dgs) do

%p         if op(i,dgs)<=1 then

%p             a := a+1 ;

%p         else

%p             a := a-1 ;

%p         end if;

%p     end do:

%p     a ;

%p end proc: # _R. J. Mathar_, Oct 16 2015

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

%K base,sign

%O 1,3

%A _Clark Kimberling_