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Search: id:A113469
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| A113469 |
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a(0)=1. a(n) = number of positive integers <= n that are not coprime to a(n-1). |
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+0
1
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| 1, 0, 2, 1, 0, 5, 1, 0, 8, 4, 5, 2, 6, 8, 7, 2, 8, 8, 9, 6, 13, 1, 0, 23, 1, 0, 26, 14, 16, 14, 17, 1, 0, 33, 13, 2, 18, 24, 25, 7, 5, 8, 21, 18, 29, 1, 0, 47, 1, 0, 50, 30, 38, 27, 18, 36, 37, 1, 0, 59, 1, 0, 62, 32, 32, 32, 33, 26, 37, 1, 0, 71, 1, 0, 74, 38, 40, 46, 41, 1, 0
(list; graph; listen)
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OFFSET
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0,3
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EXAMPLE
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a(8) = 8. So a(9) = the number of positive integers <= 9 that are not coprime to 8 (ie that are divisible by 2). So a(9) = 4.
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MAPLE
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A113469 := proc(n) option remember ; local a, i, aprev ; if n= 0 then RETURN(1) ; fi ; a :=0 ; aprev := A113469(n-1) ; for i from 1 to n do if gcd(i, aprev) <> 1 or aprev=0 then a := a+1 ; fi ; od ; RETURN(a) ; end: for n from 0 to 80 do printf("%d, ", A113469(n)) ; od ; - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jun 07 2007
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CROSSREFS
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Sequence in context: A077929 A086095 A112334 this_sequence A060137 A133727 A103185
Adjacent sequences: A113466 A113467 A113468 this_sequence A113470 A113471 A113472
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet (qq-quet(AT)mindspring.com), May 10 2007
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EXTENSIONS
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More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jun 07 2007
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