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Search: id:A063084
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| 0, -1, -1, 2, -2, 3, -3, 4, 4, 4, -6, 5, -7, 6, 6, 6, -10, 7, -11, 8, 8, 8, -14, 9, 9, 9, 9, 9, -19, 10, -20, 11, 11, 11, 11, 11, -25, 12, 12, 12, -28, 13, -29, 14, 14, 14, -32, 15, 15, 15, 15, 15, -37, 16, 16, 16, 16, 16, -42, 17, -43, 18, 18, 18, 18, 18, -48, 19, 19, 19, -51, 20, -52, 21, 21, 21, 21, 21, -57, 22, 22, 22, -60, 23, 23
(list; graph; listen)
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OFFSET
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1,4
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COMMENT
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To define as positive sequence let C(n)= A062298; f(a) = Pi(a) if a is nonprime, f(a)= C(a) if a is prime. [From daniel tisdale (daniel6874(AT)gmail.com), Nov 07 2008]
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REFERENCES
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G. A. Kudrevatow, (1970): Exercises in Number Theory. Problem 488; page 56; Prosveshenie, Moscow [in Russian].
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LINKS
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Harry J. Smith, Table of n, a(n) for n=1,...,1000
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EXAMPLE
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The function is positive for composite and negative for prime numbers. It is zero at n=1.
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PROGRAM
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(PARI) { for (n=1, 1000, if (n>1, a=primepi(n-1)*n - primepi(n)*(n-1), a=0); write("b063084.txt", n, " ", a) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Aug 17 2009]
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CROSSREFS
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Cf. A000720, A000027, A010051, A061397, A000040, A002808.
Sequence in context: A132924 A076890 A103358 this_sequence A127079 A080251 A167232
Adjacent sequences: A063081 A063082 A063083 this_sequence A063085 A063086 A063087
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KEYWORD
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sign
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu), Aug 06 2001
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