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A074057
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2*phi(n-2)-(n-1).
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0
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0, -1, 0, -1, 2, -3, 4, -1, 2, -3, 8, -5, 10, -3, 0, -1, 14, -7, 16, -5, 2, -3, 20, -9, 14, -3, 8, -5, 26, -15, 28, -1, 6, -3, 12, -13, 34, -3, 8, -9, 38, -19, 40, -5, 2, -3, 44, -17, 34, -11, 12, -5, 50, -19, 24, -9, 14, -3, 56, -29, 58, -3, 8, -1, 30, -27, 64, -5, 18, -23, 68, -25, 70, -3, 4, -5, 42, -31, 76, -17, 26, -3, 80
(list; graph; refs; listen; history; internal format)
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OFFSET
| 3,5
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COMMENTS
| Conjecture : a(n)=0 if and only if n is a Fermat prime
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FORMULA
| a(n)=-1 if n is of the form 2^x+2 a(n)=-3 if n is in a subsequence b(k) = 8, 12, 16, 24, 28, 36, 40, 48, 60, 64, 76, 84, 88, 96..( b(k) seems to be asymptotic to c*n*log(n) with c=2.28..)
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CROSSREFS
| Sequence in context: A033925 A064866 A024855 * A163258 A141063 A138223
Adjacent sequences: A074054 A074055 A074056 * A074058 A074059 A074060
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KEYWORD
| easy,sign
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AUTHOR
| Benoit Cloitre (benoit7848c(AT)orange.fr), Sep 15 2002
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