A196096 Occurrences of '11' in base 3 expansion of n.

0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 2, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 1, 2, 3, 2, 1, 1, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 2, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1

Offset

0,14

Comments

Occurrences of '11' in A007089(n). This is to base 3 and A007089 as A014081 is to base 2 A007088.

First occurrence of k>0 = 4, 13, 40, 121, 364, ..., = A003462(k). (* Robert G. Wilson v, Sep 27 2011 *)

Links

T. D. Noe, Table of n, a(n) for n = 0..1000

Example

a(4) = 1 because 4 in base 3 is "11" which has one instance of "11".
a(13) = 2 because the number 13 in base 3 is "111" which has two substrings of "11".

Maple

A196096 := proc(n)
        local a, dgs3 ;
        a := 0 ;
        dgs3 := convert(n, base, 3) ;
        for i from 1 to nops(dgs3)-1 do
                if op(i, dgs3)=1 and op(i+1, dgs3)=1 then
                        a := a+1 ;
                end if;
        end do;
        a ;
end proc:
seq(A196096(n), n=0..80) ; # R. J. Mathar, Sep 28 2011

Mathematica

f[n_] := Count[ Partition[ IntegerDigits[ n, 3], 2, 1], {1, 1}]; Array[f, 100, 0] (* Robert G. Wilson v, Sep 27 2011 *)

Crossrefs

Cf. A007089, A014081.

Sequence in context: A037878 A107652 A186734 * A249344 A067150 A356995

Adjacent sequences: A196093 A196094 A196095 * A196097 A196098 A196099

Keyword

easy,nonn

Author

Jonathan Vos Post, Sep 27 2011

Status

approved