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 A153078 Number of values of m such that sigma(m) = A002110(n) where A002110(n) is the product of the first n primes. 2
 0, 1, 1, 2, 2, 5, 2, 4, 5, 3, 7, 5, 10, 2, 8, 4, 5, 6, 11, 32, 42, 68, 24, 87 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,4 LINKS 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. FORMULA a(n) = A054973(A002110(n)). - Ray Chandler, Dec 28 2008 EXAMPLE 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. CROSSREFS Cf. A000203, A002110, A153076, A153077. Sequence in context: A245635 A111861 A004543 * A245565 A233468 A076200 Adjacent sequences: A153075 A153076 A153077 * A153079 A153080 A153081 KEYWORD nonn,more AUTHOR Donovan Johnson, Dec 19 2008 EXTENSIONS a(12)-a(21) from Ray Chandler, Dec 28 2008 a(22)-a(24) from Max Alekseyev, Jan 27 2012 STATUS approved

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Last modified February 1 07:16 EST 2023. Contains 359981 sequences. (Running on oeis4.)