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A073111
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Number of permutations p of (1,2,3,...,n) such that 1^p(1)+2^p(2)+3^p(3)+...+n^p(n) is prime.
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0
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0, 2, 0, 0, 35, 211, 0, 0, 56204, 337661, 0, 0, 454113487
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OFFSET
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1,2
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COMMENTS
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a(4*k)=a(4*k+3)=0
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LINKS
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EXAMPLE
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For n=3: permutations (1,3,2), (3,1,2), (2,3,1), (2,1,3) are OK since 1^1+2^3+3^2=13, 1^3+2^1+3^2=11, 1^2+2^3+3^1=11 and 1^2+2^1+3^3=13, hence a(3)=4.
For n=2: both permutations (1,2), (2,1) are OK since 1^1+2^2=5 and 1^2+2^1=3; hence a(2)=2.
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PROG
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(PARI) a(n)=sum(k=1, n!, if(isprime(sum(i=1, n, i^component(numtoperm(n, k), i)))-1, 0, 1))
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CROSSREFS
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KEYWORD
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more,nonn
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AUTHOR
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EXTENSIONS
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a(10) and a(11) from Mohammed Bouayoun (bouyao(AT)wanadoo.fr), Mar 29 2004
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STATUS
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approved
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