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Search: id:A152986
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| A152986 |
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Sum of proper divisors minus the number of proper divisors of pentagonal number A000326(n). |
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+0
1
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| 0, 0, 11, 11, 10, 18, 67, 71, 60, 32, 187, 351, 30, 46, 519, 337, 128, 220, 577, 483, 366, 286, 507, 1153, 248, 336, 2489, 847, 70, 818, 871, 2181, 1108, 116, 2861, 2275, 694, 130, 2763, 3645, 100, 2352, 2823, 1863, 2278, 158, 3607, 6617, 636, 920, 6181, 4019
(list; graph; listen)
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OFFSET
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1,3
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LINKS
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B. D. Swan, Table of n, a(n) for n=1,...,10000
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FORMULA
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a(n)=A001065(A000326(n))-A032741(A000326(n)) = A152770(A000326(n)).
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MAPLE
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A000326 := proc(n) n*(3*n-1)/2 ; end: A000203 := proc(n) numtheory[sigma](n) ; end: A000005 := proc(n) numtheory[tau](n) ; end: A152770 := proc(n) A000203(n)-A000005(n)-n+1 ; end: A152986 := proc(n) A152770(A000326(n)) ; end: for n from 1 to 80 do printf("%a, ", A152986(n)) ; od: [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jan 03 2009]
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CROSSREFS
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Cf. A000005, A000203, A000326, A001065, A032741, A152770.
Sequence in context: A135684 A126610 A087380 this_sequence A087994 A100755 A045538
Adjacent sequences: A152983 A152984 A152985 this_sequence A152987 A152988 A152989
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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 22 2008
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EXTENSIONS
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Extended by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jan 03 2009
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