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A153078
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Number of values of m such that sigma(m) = A002110(n) where A002110(n) is the product of the first n primes.
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2
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0, 1, 1, 2, 2, 5, 2, 4, 5, 3, 7, 5, 10, 2, 8, 4, 5, 6, 11, 32, 42, 68, 24, 87
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OFFSET
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1,4
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LINKS
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Table of n, a(n) for n=1..24.
Max A. Alekseyev, Computing the Inverses, their Power Sums, and Extrema for Euler's Totient and Other Multiplicative Functions. Journal of Integer Sequences, Vol. 19 (2016), Article 16.5.2.
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FORMULA
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a(n) = A054973(A002110(n)). - Ray Chandler, Dec 28 2008
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EXAMPLE
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a(10) = 3 because 2388809736, 3450503048 and 3696967556 are the only numbers with a sigma value = A002110(10). A002110(10) = 6469693230 = 2*3*5*7*11*13*17*19*23*29.
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CROSSREFS
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Cf. A000203, A002110, A153076, A153077.
Sequence in context: A245635 A111861 A004543 * A245565 A233468 A076200
Adjacent sequences: A153075 A153076 A153077 * A153079 A153080 A153081
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KEYWORD
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nonn,more
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AUTHOR
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Donovan Johnson, Dec 19 2008
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EXTENSIONS
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a(12)-a(21) from Ray Chandler, Dec 28 2008
a(22)-a(24) from Max Alekseyev, Jan 27 2012
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STATUS
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approved
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