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Search: id:A152990
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| A152990 |
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Sum of proper divisors minus the number of proper divisors of Fibonacci number A000045(n). |
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+0
4
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| 0, 0, 0, 0, 0, 4, 0, 8, 17, 14, 0, 245, 0, 40, 499, 542, 0, 2801, 148, 5316, 6771, 286, 0, 110809, 18032, 752, 124327, 155934, 0, 1310617, 2972, 1213164, 1821955, 5166, 2697336, 33280689, 506376, 1416024, 32030851, 106878198, 62156, 295708841, 0
(list; graph; listen)
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OFFSET
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1,6
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COMMENT
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Note that, if a(n)<>0 then Fibonacci number A000045(n) is a composite number (A002808), otherwise A000045(n) is a non-composite number (A008578). See A152770.
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LINKS
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B. D. Swan, Table of n, a(n) for n=1,...,80
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FORMULA
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a(n) = A000203(A000045(n))-A000005(A000045(n))-n+1 = A001065(A000045(n))-A032741(A000045(n)) = A152770(A000045(n)).
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EXAMPLE
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a(8)=8 because Fibonacci(8)=21, the proper divisors of 21 are 1,3 and 7; consequently, a(8)=1+3+7-3=8. [From Emeric Deutsch (deutsch(AT)duke.poly.edu), Jan 02 2009]
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MAPLE
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with(combinat): with(numtheory): seq(sigma(fibonacci(n))-fibonacci(n)-tau(fibonacci(n))+1, n = 1 .. 45); [From Emeric Deutsch (deutsch(AT)duke.poly.edu), Jan 02 2009]
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CROSSREFS
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Cf. A000005, A000045, A000203, A001065, A002808, A032741, A008578, A152770.
Sequence in context: A159468 A010769 A145831 this_sequence A019249 A013440 A013496
Adjacent sequences: A152987 A152988 A152989 this_sequence A152991 A152992 A152993
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KEYWORD
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nonn
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AUTHOR
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Omar E. Pol (info(AT)polprimos.com), Dec 20 2008
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EXTENSIONS
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Extended by Emeric Deutsch (deutsch(AT)duke.poly.edu), Jan 02 2009
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