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Search: id:A070965
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| A070965 |
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a(1) = 1; a(n+1) = sum{k|n} a(k) * mu(k), where the sum is over the positive divisors, k, of n; and mu(k) is the Moebius function. |
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+0
4
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| 1, 1, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, -1, 0, 0, 1, 1, 0, 1, 1, 0, 1, 1, 1, 0, 1, -1, 2, -1, 2, 0, 0, 0, 0, 1, 0, -1, -1, 1, 0, 1, 0, 0, 0, 0, 1, 1, 0, 1, 2, 0, 1, 1, 1, -1, -1, 0, 1, -1, 2, 3, 1, 0, 0, 1, 0, 0, 1, -1, 2, 1, 0, -1, 0, -1, -2, 2, -1, 1, 1, 0, 1, 1, 2, 1, 3, 0, 1, -1, -2, 0, 2, 2, 2, 1, 0, -1, 0, 1, 0, 2, -1, 0
(list; graph; listen)
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OFFSET
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1,30
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COMMENT
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Conjecture: all integers are present - Edwin Clark Aug 20 2004
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LINKS
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Leroy Quet, Home Page (listed in lieu of email address)
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EXAMPLE
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a(7) = a(1) mu(1) + a(2) mu(2) + a(3) mu(3) + a(6) mu(6) = 1 - 1 - 0 + 1 = 1 because 1, 2, 3 and 6 are the divisors of 6.
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MAPLE
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a:=proc(n) option remember; add(numtheory[mobius](i)*a(i), i in numtheory[divisors](n-1)) end: a(1):=1: seq(a(n), n=1..100); (from Alec Mihailovs Aug 20 2004)
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MATHEMATICA
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a[1] = a[2] = 1; a[n_] := a[n] = Block[{d = Divisors[n - 1]}, Plus @@ (MoebiusMu[d]*a /@ d)]; Table[ a[n], {n, 105}] (from Robert G. Wilson v Aug 21 2004)
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CROSSREFS
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Adjacent sequences: A070962 A070963 A070964 this_sequence A070966 A070967 A070968
Sequence in context: A164810 A089538 A152439 this_sequence A079548 A079071 A050602
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KEYWORD
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sign
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AUTHOR
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Leroy Quet, May 16 2002
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