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 A122810 Number of distinct prime factors of the smallest odd number with exactly n divisors. 6
 0, 1, 1, 2, 1, 2, 1, 3, 2, 2, 1, 3, 1, 2, 2, 3, 1, 3, 1, 3, 2, 2, 1, 4, 2, 2, 3, 3, 1, 3, 1, 4, 2, 2, 2, 4, 1, 2, 2, 4, 1, 3, 1, 3, 3, 2, 1, 5, 2, 3, 2, 3, 1, 4, 2, 4, 2, 2, 1, 4, 1, 2, 3, 5, 2, 3, 1, 3, 2, 3, 1, 5, 1, 2, 3, 3, 2, 3, 1, 5, 4, 2, 1, 4, 2, 2, 2, 4, 1, 4, 2, 3, 2, 2, 2, 5, 1, 3, 3, 4, 1, 3, 1, 4, 3 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,4 COMMENTS a(n) = 1 iff n is prime. LINKS Hans Havermann, Table of n, a(n) for n = 1..2000 (using the b-file of A038547 provided by Don Reble) FORMULA a(n) = omega(A038547(n)), where omega(n) = A001221(n). MATHEMATICA PrimeNu[Table[Select[Range[1, 532000, 2], DivisorSigma[0, #] == k + 1 &, 1], {k, 0, 15}] // Flatten] (* G. C. Greubel, May 07 2017 *) CROSSREFS Cf. A001221, A038547, A122375. Sequence in context: A125030 A116479 A318322 * A179953 A277013 A305822 Adjacent sequences:  A122807 A122808 A122809 * A122811 A122812 A122813 KEYWORD nonn AUTHOR Ray Chandler, Sep 22 2006 EXTENSIONS Typo in A_number fixed by Matthew Vandermast, May 03 2014 STATUS approved

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Last modified August 2 15:11 EDT 2021. Contains 346428 sequences. (Running on oeis4.)