A023706 Numbers with a single 0 in their base 4 expansion.

0, 4, 8, 12, 17, 18, 19, 20, 24, 28, 33, 34, 35, 36, 40, 44, 49, 50, 51, 52, 56, 60, 69, 70, 71, 73, 74, 75, 77, 78, 79, 81, 82, 83, 84, 88, 92, 97, 98, 99, 100, 104, 108, 113, 114, 115, 116, 120, 124, 133, 134, 135, 137, 138, 139, 141

Offset: 1

Author

Olivier Gérard

Keywords

• nonn
• base
• easy

Comments

Each member of the sequence is either 4*a+b for a in the sequence and b in {1,2,3}, or 4*a for a in A023705. - Robert Israel, Oct 04 2018

Links

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

Crossrefs

Cf. A023705.

Programs

Maple

R23705:= {1,2,3}:
R:= {}: A:= 0;
for i from 1 to 4 do
  R:= map(t ->4*t, R23705) union map(t -> (4*t+1,4*t+2,4*t+3), R);
  R23705:= map(t -> (4*t+1,4*t+2,4*t+3), R23705);
  A:= A, op(sort(convert(R,list)));
od:
A; # Robert Israel, Oct 04 2018

Mathematica

Select[ Range[ 0, 160 ], (Count[ IntegerDigits[ #, 4 ], 0 ]==1)& ]

PARI

isok(n) = (n==0) || (#select(x->(x==0), digits(n, 4)) == 1); \\ Michel Marcus, Oct 04 2018