A004751 Binary expansion contains 001.

9, 17, 18, 19, 25, 33, 34, 35, 36, 37, 38, 39, 41, 49, 50, 51, 57, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 81, 82, 83, 89, 97, 98, 99, 100, 101, 102, 103, 105, 113, 114, 115, 121, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn
• base
• easy

Examples

			19 is in the sequence because 19 = 10011_2 and '10011' has '001' as one of its substrings. - _Indranil Ghosh_, Feb 11 2017
		

Links

• Indranil Ghosh, Table of n, a(n) for n = 1..32769
• Index entries for 2-automatic sequences.

Crossrefs

Cf. A004748, A004749, A004750, A004752, A004753.

Programs

Mathematica

Select[Range@ 139, Length@ SequencePosition[IntegerDigits[#, 2], {0, 0, 1}] > 0 &] (* Version 10.1, or *)
Select[Range@ 139, MemberQ[Partition[IntegerDigits[#, 2], 3, 1], {0, 0, 1}] &] (* Michael De Vlieger, Feb 11 2017 *)
Select[Range[150],SequenceCount[IntegerDigits[#,2],{0,0,1}]>0&] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jun 15 2018 *)

PARI

is(n)=while(n>8, if(bitand(n,7)==1, return(1)); n>>=1); 0 \\ Charles R Greathouse IV, Feb 11 2017

Python

i=j=0
while j<=100:
    if "001" in bin(i)[2:]:
        print(str(j)+" "+str(i))
        j+=1
    i+=1 # Indranil Ghosh, Feb 11 2017

Formula

a(n) ~ n. - Charles R Greathouse IV, Oct 23 2015

Extensions

Offset corrected by Charles R Greathouse IV, Feb 11 2017