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Search: id:A152987
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| A152987 |
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Sum of proper divisors minus the number of proper divisors of the number of partitions of n, A000041(n). |
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+0
1
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| 0, 0, 0, 0, 0, 0, 6, 11, 35, 47, 57, 16, 0, 98, 187, 146, 176, 184, 525, 326, 1525, 1007, 254, 1632, 1275, 4261, 3311, 2859, 1476, 7489, 4383, 4408, 7624, 9859, 7450, 0, 5428, 9086, 38472, 50191, 29898, 33867, 41264, 22030, 47947, 109323, 107783, 77168
(list; graph; listen)
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OFFSET
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1,7
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COMMENT
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Note that, if a(n)<>0 then the number of partitions of n (A000041(n)) is a composite number (A002808), otherwise A000041(n) is a non-composite number (A008578). See A152770.
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FORMULA
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a(n) = A001065(A000041(n))-A032741(A000041(n)) = A152770(A000041(n)).
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MAPLE
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A000041 := proc(n) combinat[numbpart](n) ; end: A001065 := proc(n) numtheory[sigma](n)-n ; end: A032741 := proc(n) if n = 0 then 0; else numtheory[tau](n)-1 ; fi; end: A152987 := proc(n) local np ; np := A000041(n) ; A001065(np)-A032741(np) ; end: for n from 1 to 80 do printf("%d, ", A152987(n)) ; end: [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jan 22 2009]
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CROSSREFS
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Cf. A000005, A000041, A000203, A001065, A002808, A032741, A008578, A152770.
Sequence in context: A105508 A114960 A151790 this_sequence A100093 A166702 A130667
Adjacent sequences: A152984 A152985 A152986 this_sequence A152988 A152989 A152990
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KEYWORD
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easy,nonn
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AUTHOR
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Omar E. Pol (info(AT)polprimos.com), Dec 21 2008
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EXTENSIONS
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More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jan 22 2009
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