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A143221
a(0)=1. For n >=1, a(n) = 0 if the binary representation of n occurs at least once in the concatenation of (a(0),a(1),...,a(n-1)). a(n) = 1 otherwise.
3
1, 0, 0, 1, 0, 1, 1, 1, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 1, 1, 0, 1, 1, 0, 0, 1, 1, 1, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 1, 0, 1, 1, 1, 0, 0, 0, 0, 1, 0, 1, 0, 1, 1, 0, 1, 1, 1, 1, 0, 1, 0, 1, 1, 1, 0, 0, 1, 0, 1, 1, 0, 1, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 1, 1, 1, 0, 1, 0, 1
OFFSET
0,1
LINKS
EXAMPLE
The binary representation of 21 is 10101. This occurs in the concatenation of terms a(0) through a(20) like so: 10010111(10101)00010010. So a(21) = 0.
MAPLE
S:= "1":
for n from 1 to 1000 do
if StringTools:-Search(convert(convert(n, binary), string), S) = 0 then S:= cat(S, "1") else S:= cat(S, "0") fi
od:
map(parse, StringTools:-Explode(S)); # Robert Israel, May 06 2018
MATHEMATICA
f[l_List]:=Append[l, Boole[StringPosition[ToString[FromDigits[l]], ToString[FromDigits[IntegerDigits[Length[l], 2]]]]=={}]]; Nest[f, {1}, 125] (* Ray Chandler, Nov 09 2008 *)
CROSSREFS
Sequence in context: A104105 A295889 A347523 * A325899 A126999 A306862
KEYWORD
base,nonn
AUTHOR
Leroy Quet, Jul 30 2008
EXTENSIONS
Extended by Ray Chandler, Nov 09 2008
STATUS
approved