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A086936 Number of primes between n and p(n) inclusive. 0
1, 2, 2, 2, 3, 3, 4, 4, 5, 6, 7, 7, 8, 8, 9, 10, 11, 11, 12, 12, 13, 14, 15, 15, 16, 17, 18, 19, 20, 20, 21, 21, 22, 23, 24, 25, 26, 26, 27, 28, 29, 29, 30, 30, 31, 32, 33, 33, 34, 35, 36, 37, 38, 38, 39, 40, 41, 42, 43, 43, 44, 44, 45, 46, 47, 48, 49, 49, 50, 51, 52, 52, 53, 53 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Or number of nonprimes A141468<n. [From Juri-Stepan Gerasimov, Nov 19 2009]

LINKS

Table of n, a(n) for n=1..74.

FORMULA

a(n)=sum{k=0..n, (1+mu(if(prime(k), k, 1)))/2} [offset 0] - Paul Barry, May 10 2005

a(n)=1+n-A000720(n). [From Juri-Stepan Gerasimov, Nov 19 2009]

CROSSREFS

Cf. A000027, A000720, A141468. [From Juri-Stepan Gerasimov, Nov 19 2009]

Sequence in context: A035429 A280169 A018117 * A214129 A280151 A094990

Adjacent sequences:  A086933 A086934 A086935 * A086937 A086938 A086939

KEYWORD

easy,nonn

AUTHOR

Zak Seidov, Sep 22 2003

STATUS

approved

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Last modified October 31 11:50 EDT 2020. Contains 338101 sequences. (Running on oeis4.)