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A018783
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Number of partitions of n into parts having a common factor.
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68
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0, 0, 1, 1, 2, 1, 4, 1, 5, 3, 8, 1, 14, 1, 16, 9, 22, 1, 38, 1, 45, 17, 57, 1, 94, 7, 102, 30, 138, 1, 218, 1, 231, 58, 298, 21, 451, 1, 491, 103, 644, 1, 919, 1, 1005, 203, 1256, 1, 1784, 15, 1993, 299, 2439, 1, 3365, 62, 3735, 492, 4566, 1, 6252, 1, 6843, 819, 8349, 107, 11096
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OFFSET
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0,5
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LINKS
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FORMULA
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MAPLE
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with(numtheory): with(combinat):
a:= n-> `if`(n=0, 0,
numbpart(n) -add(mobius(n/d)*numbpart(d), d=divisors(n))):
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MATHEMATICA
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PROG
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(PARI) a(n) = - sumdiv(n, d, (d<n)*moebius(n/d)*numbpart(d)); \\ Michel Marcus, Oct 07 2017
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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