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Search: id:A072950
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| A072950 |
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Number of permutations p of (1,2,3,...,n) such that at least one value of abs(k-p(k))) is prime. |
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+0
1
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| 0, 0, 3, 19, 107, 691, 4929, 39958, 361114, 3617842, 39839167, 478446607
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OFFSET
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1,3
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PROGRAM
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(PARI) a(n)=sum(k=1, n!, if(sum(i=1, n, isprime(abs(i-component(numtoperm(n, k)), i))), 1, 0))
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CROSSREFS
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Adjacent sequences: A072947 A072948 A072949 this_sequence A072951 A072952 A072953
Sequence in context: A095120 A151539 A089164 this_sequence A130425 A103005 A162354
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KEYWORD
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more,nonn
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AUTHOR
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Benoit Cloitre (benoit7848c(AT)orange.fr), Aug 20 2002
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EXTENSIONS
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More terms from Ryan Propper (rpropper(AT)stanford.edu), Jul 21 2006
Definition corrected by Franklin T. Adams-Watters, Dec 07 2006
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