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 A193348 Number of odd divisors of tau(n). 2
 1, 1, 1, 2, 1, 1, 1, 1, 2, 1, 1, 2, 1, 1, 1, 2, 1, 2, 1, 2, 1, 1, 1, 1, 2, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 3, 1, 1, 1, 1, 1, 1, 1, 2, 2, 1, 1, 2, 2, 2, 1, 2, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 2, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 2, 2, 1, 1, 1, 2, 2, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 2, 1, 2, 2, 3 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,4 COMMENTS a(n) = A001227(A000005(n)). [Reinhard Zumkeller, Jul 25 2011] LINKS Reinhard Zumkeller, Table of n, a(n) for n = 1..10000 EXAMPLE a(36) = 3 because tau(36) = 9 and the 3 odd divisors are {1, 3, 9}. MATHEMATICA f[n_] := Block[{d = Divisors[DivisorSigma[0, n]]}, Count[OddQ[d], True]]; Table[f[n], {n, 80}] PROG (PARI) a(n)=sumdiv(sigma(n, 0), d, d%2); (PARI) a(n)=n=numdiv(n); numdiv(n>>valuation(n, 2)) \\ Charles R Greathouse IV, Jul 30 2011 CROSSREFS Cf. A000005. Sequence in context: A294932 A327804 A056624 * A263723 A318498 A093997 Adjacent sequences:  A193345 A193346 A193347 * A193349 A193350 A193351 KEYWORD nonn,easy AUTHOR Michel Lagneau, Jul 23 2011 STATUS approved

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Last modified September 22 15:04 EDT 2021. Contains 347607 sequences. (Running on oeis4.)