A045058 Numbers whose base-4 representation contains exactly four 0's and one 2.

512, 1026, 1032, 1056, 1152, 1536, 2049, 2051, 2052, 2060, 2064, 2096, 2112, 2240, 2304, 2816, 3074, 3080, 3104, 3200, 3584, 4102, 4105, 4107, 4110, 4114, 4120, 4129, 4131, 4132, 4140, 4146, 4152, 4162, 4168, 4192, 4225

Offset

1,1

Links

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

Maple

dmax:= 8: # to get all terms < 4^dmax
T[1, 1, 0]:= {}: T[1, 0, 1]:= {2}: T[1, 0, 0]:= {1, 3}:
for d from 2 to dmax do
  for a from 0 to max(d-1, 4) do
    for b from 0 to max(d-a, 1) do
       T[d, a, b]:= {}:
       if a + b <= d-1 and a < d-1 then
         T[d, a, b]:= T[d, a, b] union map(t -> (4*t+1, 4*t+3), T[d-1, a, b])
       fi;
       if a >= 1 then
         T[d, a, b]:= T[d, a, b] union map(t -> 4*t, T[d-1, a-1, b])
       fi;
       if b >= 1 and a < d-1 then
         T[d, a, b]:= T[d, a, b] union map(t -> 4*t+2, T[d-1, a, b-1])
       fi;
od od od:
sort([seq](op(T[d, 4, 1]), d=5..dmax)); # Robert Israel, Jun 29 2017

Mathematica

Select[Range[4500], DigitCount[#, 4, 0]==4&&DigitCount[#, 4, 2]==1&] (* Harvey P. Dale, May 26 2018 *)

Crossrefs

Cf. A007090.

Sequence in context: A066648 A043423 A341886 * A220017 A234879 A202454

Adjacent sequences: A045055 A045056 A045057 * A045059 A045060 A045061

Keyword

nonn,base

Author

Clark Kimberling

Status

approved