A143220 a(0)=1. For n >=1, a(n) = 1 if the binary representation of n occurs at least once in the concatenation of (a(0),a(1),...,a(n-1)). a(n) = 0 otherwise.

1, 1, 0, 1, 0, 1, 1, 0, 0, 0, 1, 1, 1, 1, 0, 1, 0, 1, 0, 0, 1, 1, 1, 0, 1, 0, 1, 0, 0, 1, 1, 0, 0, 0, 0, 1, 0, 0, 1, 1, 0, 1, 1, 1, 1, 0, 0, 1, 1, 1, 0, 1, 0, 1, 0, 1, 0, 1, 1, 0, 1, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0

Offset

0,1

Links

Table of n, a(n) for n=0..104.

Example

The binary representation of 21 is 10101. This occurs in the concatenation of terms a(0) through a(20) like so: 1101011000111(10101)001. So a(21) = 1.

Mathematica

f[l_List]:=Append[l, Boole[StringPosition[ToString[FromDigits[l]], ToString[FromDigits[IntegerDigits[Length[l], 2]]]]!={}]]; Nest[f, {1}, 125] [From Ray Chandler, Nov 09 2008]

Crossrefs

Cf. A118268, A143221, A143222.

Sequence in context: A176723 A189126 A118268 * A189163 A189129 A267269

Adjacent sequences: A143217 A143218 A143219 * A143221 A143222 A143223

Keyword

base,nonn

Author

Leroy Quet, Jul 30 2008

Extensions

Extended by Ray Chandler, Nov 09 2008

Status

approved