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A152992
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a(n) = sigma(n) - d(n) - pi(n).
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2
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0, 0, 0, 2, 1, 5, 2, 7, 6, 10, 5, 17, 6, 14, 14, 20, 9, 26, 10, 28, 20, 24, 13, 43, 19, 29, 27, 41, 18, 54, 19, 46, 33, 39, 33, 71, 24, 44, 40, 70, 27, 75, 28, 64, 58, 54, 31, 99, 39, 72, 53, 77, 36, 96, 52, 96, 60, 70, 41, 139, 42, 74, 80, 102, 62, 118, 47, 101, 73, 117, 50
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,4
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LINKS
| Harvey P. Dale, Table of n, a(n) for n = 1..1000
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FORMULA
| a(n) = A000203(n)-A000005(n)-A000720(n) = A065608(n)-A000720(n) = A152991(n)-A000005(n).
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EXAMPLE
| a(15)=24-4-6=14 because the sum of divisors of 15 is 1+3+5+15=24, the number of divisors of 15 is 4 (1,3,5,15) and the number of primes not exceeding 15 is 6 (2,3,5,7,11,13). [From Emeric Deutsch (deutsch(AT)duke.poly.edu), Dec 30 2008]
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MAPLE
| with(numtheory): seq(sigma(n)-tau(n)-pi(n), n = 1 .. 75); [From Emeric Deutsch (deutsch(AT)duke.poly.edu), Dec 30 2008]
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MATHEMATICA
| Table[DivisorSigma[1, n]-DivisorSigma[0, n]-PrimePi[n], {n, 75}] (* From Harvey P. Dale, Sep 19 2011 *)
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CROSSREFS
| Cf. A000005, A000203, A000720, A065608, A152770, A152991.
Sequence in context: A087620 A178913 A142721 * A185727 A070951 A076937
Adjacent sequences: A152989 A152990 A152991 * A152993 A152994 A152995
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KEYWORD
| easy,nonn
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AUTHOR
| Omar E. Pol (info(AT)polprimos.com), Dec 19 2008, Dec 31 2008
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EXTENSIONS
| Corrected and extended by Emeric Deutsch (deutsch(AT)duke.poly.edu), Dec 30 2008
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