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Search: id:A162201
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| 0, 2, 0, 3, -1, 3, -1, 3, -3, 4, -2, 5, -1, 3, -3, 6, -2, 4, -3, 3, -2, 5, -3, 7, -4, 3, -1, 3, -1, 9, -7, 5, -2, 6, -4, 4, -4, 5, -3, 6, -2, 6, -4, 3, -1, 7, -10, 8, -1, 3, -3, 4, -4, 8, -4, 6, -2, 4, -3, 3, -4, 12, -7, 3, -1, 9, -8, 8, -4, 3, -3, 7, -5, 6, -3, 5, -5, 6, -4, 9, -4, 6, -4, 4, -3
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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The absolute value of a(n) is also the length of the n-th vertical edge in the graph of the "mountain path" function for prime numbers.
See A162200 for the length of the n-th horizontal component.
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LINKS
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O. E. Pol, Graph of the mountain path function for prime numbers
O. E. Pol, Illustration: The mountain path of the primes
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FORMULA
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a(n)=A052288(n-1) if n>=2, n even. a(n)=2-A052288(n-1) if n>=3, n odd. [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jul 15 2009]
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MAPLE
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A031131 := proc(n) ithprime(n+2)-ithprime(n) ; end: A052288 := proc(n) A031131(n)/2 ; end: A160173 := proc(n) if n <= 2 then 2*(n-1); elif n mod 2 = 0 then A052288(n-1) ; else 2-A052288(n-1) ; fi; end: seq(A160173(n), n=1..150) ; [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jul 15 2009]
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CROSSREFS
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Cf. A000040, A006005, A008578, A162200, A162202, A162203, A162340, A162341, A162342, A162343, A162344.
Sequence in context: A015710 A054875 A029239 this_sequence A029219 A110514 A135157
Adjacent sequences: A162198 A162199 A162200 this_sequence A162202 A162203 A162204
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KEYWORD
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easy,sign
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AUTHOR
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Omar E. Pol (info(AT)polprimos.com), Jun 28 2009
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EXTENSIONS
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Edited by Omar E. Pol (info(AT)polprimos.com), Jul 02 2009
More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jul 15 2009
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