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Search: id:A106743
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| A106743 |
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a(n) = -1 iff n is prime, a(n) = 1 iff n is not squarefree, otherwise (n is nonprime and square-free) a(n) = 0. |
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1
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| 0, -1, -1, 1, -1, 0, -1, 1, 1, 0, -1, 1, -1, 0, 0, 1, -1, 1, -1, 1, 0, 0, -1, 1, 1, 0, 1, 1, -1, 0, -1, 1, 0, 0, 0, 1, -1, 0, 0, 1, -1, 0, -1, 1, 1, 0, -1, 1, 1, 1, 0, 1, -1, 1, 0, 1, 0, 0, -1, 1, -1, 0, 1, 1, 0, 0, -1, 1, 0, 0, -1, 1, -1, 0, 1, 1, 0, 0, -1, 1, 1, 0, -1, 1, 0, 0, 0, 1, -1, 1, 0, 1, 0, 0, 0, 1, -1, 1, 1, 1, -1, 0, -1, 1, 0
(list; graph; listen)
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OFFSET
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1,1
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FORMULA
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a(n) = 1 - 0^(A001222(n)-A001221(n)) - 0^(A001222(n)-1), for n>1. - Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), May 23 2005
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PROGRAM
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(PARI) for(n=1, 105, print1(if(!issquarefree(n), 1, if(isprime(n), -1, 0)), ", "))
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CROSSREFS
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Cf. A000040 (prime), A013929 (not squarefree), A000469 (nonprime and square-free), A082926.
Sequence in context: A053867 A069513 A092248 this_sequence A011558 A100047 A080891
Adjacent sequences: A106740 A106741 A106742 this_sequence A106744 A106745 A106746
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KEYWORD
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sign
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AUTHOR
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Giovanni Teofilatto (g.teofilatto(AT)tiscalinet.it), May 16 2005
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EXTENSIONS
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Edited and extended by Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), May 16 2005
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