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A119018 a(1) = 0; a(n) is the smallest number not yet used that is not relatively prime to n nor relatively prime to a(n-1). +0
2
0, 2, 6, 4, 10, 8, 14, 12, 3, 15, 33, 9, 39, 18, 20, 16, 34, 22, 38, 24, 21, 28, 46, 26, 30, 32, 36, 40, 58, 42, 62, 44, 11, 66, 45, 27, 111, 48, 51, 54, 82, 50, 86, 52, 60, 56, 94, 64, 70, 5, 75, 65, 265, 80, 25, 35, 63, 72, 118, 68, 122, 74, 78, 76, 90, 55, 335, 85, 102, 84, 142 (list; graph; listen)
OFFSET

1,2

COMMENT

Conjecture: this sequence includes every integer greater than 1.

EXAMPLE

a(12) must have a common factor with 12 and a(11) = 33. The first few such values are 3, 6 and 9; 3 and 6 have already been used, so a(12)=9.

MAPLE

A119018 := proc(nmin) local a, anxt ; a := [0] ; while nops(a) < nmin do anxt := 1 ; n := nops(a)+1 ; while anxt in a or gcd(n, anxt) = 1 or gcd(op(-1, a), anxt) = 1 do anxt := anxt+1 ; od ; a := [op(a), anxt]; od: RETURN(a) ; end: A119018(100) ; - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Sep 07 2007

CROSSREFS

Cf. A119019.

Sequence in context: A145019 A066678 A113571 this_sequence A094748 A065879 A065880

Adjacent sequences: A119015 A119016 A119017 this_sequence A119019 A119020 A119021

KEYWORD

nonn

AUTHOR

Frank Adams-Watters (FrankTAW(AT)Netscape.net), May 08 2006

EXTENSIONS

Definition corrected by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Sep 07 2007

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.


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