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A216345 Position of the beginning of the n-th run in A000002. 6
1, 2, 4, 6, 7, 8, 10, 11, 13, 15, 16, 18, 20, 21, 22, 24, 25, 26, 28, 30, 31, 33, 34, 35, 37, 38, 40, 42, 43, 44, 46, 47, 48, 50, 51, 53, 55, 56, 58, 60, 61, 62, 64, 65, 67, 69, 70, 72, 73, 74, 76, 77, 78, 80, 82, 83, 85, 87, 88, 89, 91, 92, 94, 96, 97, 99, 101, 102, 103 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

If n is odd then the run is 1's, otherwise it's 2's.

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

FORMULA

{n: A156728(n-1)=1}. - R. J. Mathar, Sep 14 2012

a(n+1) = A054353(n)+1 = a(n) + A000002(n). - Jean-Christophe Hervé, Oct 05 2014

EXAMPLE

Kolakoski sequence starts 1221121 so we can see that this sequence begins 1,2,4,6,7.

PROG

(JavaScript)

a=new Array();

a[1]=1;  a[2]=2;  a[3]=2;

cd=1;  ap=3;

for (i=4; i<50; i++)

{

    if (a[ap]==1) a[i]=cd;

    else {a[i]=cd; a[i+1]=cd; i++}

    ap++;

    cd=3-cd;

}

/* document.write(a); document.write("<br>"); */

b=new Array();

b[1]=1;

c=2;

for (i=2; i<50; i++)

    if (a[i]!=a[i-1]) b[c++]=i;

document.write(b);

(Haskell)

a216345 n = a216345_list !! (n-1)

a216345_list = 1 : (filter (\x -> a000002 x /= a000002 (x - 1)) [2..])

-- Reinhard Zumkeller, Aug 03 2013

CROSSREFS

Cf. A000002, A054354.

Cf. A100428, A100429.

Sequence in context: A339508 A275844 A158025 * A026510 A138204 A080645

Adjacent sequences:  A216342 A216343 A216344 * A216346 A216347 A216348

KEYWORD

nonn

AUTHOR

Jon Perry, Sep 04 2012

STATUS

approved

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Last modified July 1 10:54 EDT 2022. Contains 354972 sequences. (Running on oeis4.)