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A279645 a(n) = not (n XOR (n shift 1)). 3
0, 0, 0, 1, 1, 0, 2, 3, 3, 2, 0, 1, 5, 4, 6, 7, 7, 6, 4, 5, 1, 0, 2, 3, 11, 10, 8, 9, 13, 12, 14, 15, 15, 14, 12, 13, 9, 8, 10, 11, 3, 2, 0, 1, 5, 4, 6, 7, 23, 22, 20, 21, 17, 16, 18, 19, 27, 26, 24, 25, 29, 28, 30, 31, 31, 30, 28, 29, 25, 24, 26, 27, 19, 18, 16 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,7

COMMENTS

Values of n for which A279645(n) = 0 are given by A000975(k).

Values of n for which A279645(n) = 1 are given by A097072(k) (for  k>1).

LINKS

Paolo P. Lava, Table of n, a(n) for n = 0..10000

Paolo P. Lava, First occurrence of n in A279645, for n <= 1000

Paolo P. Lava, Graph of the first 10000 terms

Paolo P. Lava, Graph of the first occurrence of n in A279645, for n <= 1000

EXAMPLE

5044 converted to base 2 is 1001110110100.

Then consider each pair of adjacent bits starting from MSD: if they are equal, 00 or 11, set 1 otherwise 0:

(1+0) -> 0

(0+0) -> 1

(0+1) -> 0

(1+1) -> 1

(1+1) -> 1

(1+0) -> 0

(0+1) -> 0

(1+1) -> 1

(1+0) -> 0

(0+1) -> 0

(1+0) -> 0

(0+0) -> 1

We get 10110010001, so a(5044) = 1425.

MAPLE

P:=proc(n) local a, b, k; a:=0; b:=convert(n, base, 2);

for k to nops(b)-1 do a:=a+((((b[k]+b[k+1]) mod 2)+1) mod 2)*2^(k-1); od; RETURN(a); end;

[seq(P(i), i=0..100)];

# alternative ( R. J. Mathar, Jun 22 2020)

A279645 := proc(n)

    local dgs, L ;

    dgs := convert(n, base, 2) ;

    L := [] ;

    for i from 2 to nops(dgs) do

        if op(i, dgs) = op(i-1, dgs) then

            L := [op(L), 1] ;

        else

            L := [op(L), 0] ;

        fi ;

    end do:

    add( op(i, L)*2^(i-1), i=1..nops(L)) ;

end proc:

CROSSREFS

Cf. A000975, A038554, A097072.

Sequence in context: A131012 A083057 A099028 * A198197 A203400 A077869

Adjacent sequences:  A279642 A279643 A279644 * A279646 A279647 A279648

KEYWORD

nonn,easy,look

AUTHOR

Paolo P. Lava, Dec 16 2016

STATUS

approved

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Last modified December 2 19:12 EST 2020. Contains 338891 sequences. (Running on oeis4.)