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A074794 Number of numbers k <=n such that tau(k) == 1 (mod 3) where tau(k) =A00005(k) is the number of divisors of k. +0
1
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; listen)
OFFSET

1,6

FORMULA

a(n) is asymptotic to c*n with c=0.36.....

PROGRAM

(PARI) a(n)=sum(k=1, n, if(numdiv(k)%3-1, 0, 1))

CROSSREFS

Sequence in context: A074796 A061070 A117695 this_sequence A048686 A090501 A126848

Adjacent sequences: A074791 A074792 A074793 this_sequence A074795 A074796 A074797

KEYWORD

nonn

AUTHOR

Benoit Cloitre (benoit7848c(AT)orange.fr), Sep 07 2002

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.


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