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Search: id:A103827
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| A103827 |
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Arithmetic means of the divisors of unitary arithmetic numbers (i.e. of those for which the arithmetic mean of the unitary divisors is an integer, A103826). |
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+0
2
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| 1, 2, 3, 3, 4, 5, 6, 5, 7, 6, 6, 9, 10, 8, 9, 12, 9, 13, 14, 10, 15, 9, 16, 12, 12, 19, 15, 14, 21, 12, 22, 15, 15, 18, 24, 17, 25, 18, 27, 21, 18, 18, 20, 30, 15, 31, 24, 20, 21, 18, 34, 24, 18, 36, 37, 26, 25, 24, 21, 40, 41, 42, 20, 27, 33, 30, 27, 45, 28, 30, 32, 36, 30, 33, 49
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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The unitary arithmetic numbers are in A103826.
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EXAMPLE
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a(8)=5 because the eighth unitary arithmetic number is A103826(8)=12, the unitary divisors of 12 are 1,3,4, and 12, and (1+3+4+12)/4=5.
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MAPLE
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with(numtheory):unitdiv:=proc(n) local A, k: A:={}: for k from 1 to tau(n) do if gcd(divisors(n)[k], n/divisors(n)[k])=1 then A:=A union {divisors(n)[k]} else A:=A fi od end:utau:=n->nops(unitdiv(n)):usigma:=n->add(unitdiv(n)[j], j=1..nops(unitdiv(n))): p:=proc(n) if type(usigma(n)/utau(n), integer)=true then usigma(n)/utau(n) else fi end:seq(p(n), n=1..109);
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CROSSREFS
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Cf. A103826, A034444, A034448.
Sequence in context: A007998 A029931 A022290 this_sequence A094182 A075699 A112330
Adjacent sequences: A103824 A103825 A103826 this_sequence A103828 A103829 A103830
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KEYWORD
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nonn
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AUTHOR
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Emeric Deutsch (deutsch(AT)duke.poly.edu), Feb 17 2005
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