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 A074794 Number of numbers k <= n such that tau(k) == 1 (mod 3) where tau(k) = A000005(k) is the number of divisors of k. 4
 1, 1, 1, 1, 1, 2, 2, 3, 3, 4, 4, 4, 4, 5, 6, 6, 6, 6, 6, 6, 7, 8, 8, 8, 8, 9, 10, 10, 10, 10, 10, 10, 11, 12, 13, 13, 13, 14, 15, 15, 15, 15, 15, 15, 15, 16, 16, 17, 17, 17, 18, 18, 18, 18, 19, 19, 20, 21, 21, 21, 21, 22, 22, 23, 24, 24, 24, 24, 25, 25, 25, 25, 25, 26, 26, 26, 27, 27 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,6 LINKS Amiram Eldar, Table of n, a(n) for n = 1..10000 FORMULA a(n) is asymptotic to c*n with c = 0.36.... MATHEMATICA Accumulate[Table[Boole[Mod[DivisorSigma[0, n], 3] == 1], {n, 1, 100}]] (* Amiram Eldar, Aug 29 2020 *) PROG (PARI) a(n)=sum(k=1, n, if(numdiv(k)%3-1, 0, 1)) CROSSREFS Cf. A000005, A074795, A074796, A211337. Sequence in context: A061070 A285879 A117695 * A234309 A306921 A048686 Adjacent sequences: A074791 A074792 A074793 * A074795 A074796 A074797 KEYWORD nonn AUTHOR Benoit Cloitre, Sep 07 2002 STATUS approved

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Last modified October 4 20:53 EDT 2023. Contains 365888 sequences. (Running on oeis4.)