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 A212640 Number of divisors of A181800(n) (n-th powerful number that is the first integer of its prime signature). 2
 1, 3, 4, 5, 6, 9, 7, 12, 8, 15, 16, 9, 18, 20, 10, 21, 24, 27, 11, 24, 25, 28, 36, 12, 27, 30, 32, 45, 13, 30, 35, 48, 36, 54, 36, 14, 33, 40, 60, 40, 63, 42, 15, 36, 45, 72, 64, 44, 72, 48, 75, 16, 39, 50, 84, 81, 49, 80, 48, 81, 54, 90, 17, 42, 55, 96, 108 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Amiram Eldar, Table of n, a(n) for n = 1..10000 FORMULA a(n) = A000005(A181800(n). EXAMPLE A181800(6) = 36 has 9 divisors (1, 2, 3, 4, 6, 9, 12, 18 and 36). Hence, a(6) = 9. CROSSREFS Cf. A181800, A000005, A212641. Sequence in context: A249798 A037348 A277898 * A333694 A364064 A338321 Adjacent sequences: A212637 A212638 A212639 * A212641 A212642 A212643 KEYWORD nonn AUTHOR Matthew Vandermast, Jun 09 2012 STATUS approved

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Last modified September 30 21:59 EDT 2023. Contains 365812 sequences. (Running on oeis4.)