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 A185894 Number of prime divisors (counted with multiplicity) of number of rings with n elements. 0
 0, 0, 1, 1, 1, 1, 2, 1, 3, 1, 2, 1, 2, 1, 2, 2, 4, 1, 2, 2, 1, 2, 2, 2, 1, 4, 1, 2, 1, 2, 1, 3, 1 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,7 COMMENTS By convention, there is 1 ring with no elements. The first value that I don't know is a(32), where the number of rings with 32 elements was said by Christof Noebauer in 2000 to be > 18590. The next value not known to me is a(64), which is where the same source gives the number of rings with 64 elements > 829826. The articles by Christof Noebauer are linked to from A027623. LINKS Eric W. Weisstein Ring FORMULA a(n) = A001222(A027623(n)). EXAMPLE a(16) = 4 because there are A027623(16) = 390 rings with 16 elements, and 390 = 2 * 3 * 5 * 13 has 4 prime divisors counted with multiplicity (in this example, each has multiplicity of 1). CROSSREFS Cf. A001222, A027623. Sequence in context: A327518 A174532 A089242 * A214180 A343073 A184166 Adjacent sequences:  A185891 A185892 A185893 * A185895 A185896 A185897 KEYWORD nonn,more,hard AUTHOR Jonathan Vos Post, Feb 05 2011 STATUS approved

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Last modified April 17 05:36 EDT 2021. Contains 343059 sequences. (Running on oeis4.)