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Search: id:A096433
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| A096433 |
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a(1)=1; for n > 1, choose a(n) so that sum_{1<=k<=n, GCD(k,n+1)=1} a(k) = 0. |
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+0
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| 1, -1, -1, 1, -1, 1, 1, -1, -1, 1, -1, 1, 3, -3, -1, 1, -3, 3, 1, -1, 1, -1, -1, -1, 5, -1, -1, -1, -1, 1, -1, 1, -3, 5, -3, 1, 7, -5, -1, -1, -9, 9, 5, 3, 3, -11, -3, 7, 7, 9, -1, -19, -7, 17, 11, 9, -7, -23, 1, -1, -1, 37, 1, -33, -1, -3, -3, 15, 27, -39, -7, 7, -9, 47, -13, -37, 11, 1, -5, 51, -9, -37, 19, 17, -5, -1, 13, -43, -5, -3, 13
(list; graph; listen)
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OFFSET
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1,13
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LINKS
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Leroy Quet, Home Page (listed in lieu of email address)
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FORMULA
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a(n)=-sum_{1<=k<=n-1, GCD(k, n+1)=1} a(k).
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EXAMPLE
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a(7)=1 since the positive integers < 8 and coprime to 8 are 1, 3, 5, 7, thus a(1) + a(3) + a(5) + a(7) = 1 - 1 - 1 + 1 = 0.
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MATHEMATICA
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a[1] = 1; a[n_] := a[n] = Block[{k = Select[ Range[n - 1], GCD[ #, n + 1] == 1 &]}, -Plus @@ (a /@ k)]; Table[ a[n], {n, 94}] (from Robert G. Wilson v Aug 24 2004)
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CROSSREFS
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Sequence in context: A125300 A126717 A124039 this_sequence A084101 A053386 A090569
Adjacent sequences: A096430 A096431 A096432 this_sequence A096434 A096435 A096436
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KEYWORD
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sign
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AUTHOR
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Leroy Quet Aug 10 2004
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EXTENSIONS
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Edited and extended by Robert G. Wilson v (rgwv(AT)rgwv.com), Aug 24 2004
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