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Search: id:A089043
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| A089043 |
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n!^2+(-1)^n : p = 2*n+1 is prime iff it divides a(n). |
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1
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| 0, 5, 35, 577, 14399, 518401, 25401599, 1625702401, 131681894399, 13168189440001, 1593350922239999, 229442532802560001, 38775788043632639999, 7600054456551997440001
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OFFSET
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0,2
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COMMENT
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p = 2*n+1 is prime iff it divides a(n) (wilson's theorem) for instance let n=5, p =11 : a(5) = 14399 = 11*1309, so 11 is prime
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FORMULA
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a(n) = n^2*(a(n-1)-(-1)^(n-1))+(-1)^n; generating function = n!^2+(-1)^n
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EXAMPLE
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a(5) = 14399 because 14399=(5!)^2+(-1)^5
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CROSSREFS
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Sequence in context: A125802 A034217 A011556 this_sequence A034236 A058015 A053420
Adjacent sequences: A089040 A089041 A089042 this_sequence A089044 A089045 A089046
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KEYWORD
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easy,nonn
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AUTHOR
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Serge Boisse (serge.boisse(AT)aviation-civile.gouv.fr), Dec 02 2003
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