

A116568


Difference between n and the absolute value of the difference between number of nonprimes not exceeding n and number of primes not exceeding n.


1



0, 2, 2, 4, 4, 6, 6, 8, 8, 8, 10, 10, 12, 12, 12, 12, 14, 14, 16, 16, 16, 16, 18, 18, 18, 18, 18, 18, 20, 20, 22, 22, 22, 22, 22, 22, 24, 24, 24, 24, 26, 26, 28, 28, 28, 28, 30, 30, 30, 30, 30, 30, 32, 32, 32, 32, 32, 32, 34, 34, 36, 36, 36, 36, 36, 36, 38, 38, 38, 38, 40, 40, 42
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OFFSET

1,2


LINKS

G. C. Greubel, Table of n, a(n) for n = 1..5000


FORMULA

a(n) = n  Abs[A097454(n)].


EXAMPLE

a(11)=10 because the nonprimes not exceeding 11 are 1,4,6,8,9 and 10, the primes not exceeding 11 are 2,3,5,7 and 11 and 11abs(65)=10.


MAPLE

with(numtheory): seq(nabs(n2*pi(n)), n=1..73);


MATHEMATICA

Table[nAbs[2*PrimePi[n]n], {n, 80}] (* Harvey P. Dale, Oct 08 2015 *)


PROG

(PARI) for(n=1, 50, print1(n  abs(2*primepi(n)  n) , ", ")) \\ G. C. Greubel, Sep 20 2017


CROSSREFS

Cf. A097454.
Sequence in context: A179291 A004079 A096494 * A239933 A061106 A319399
Adjacent sequences: A116565 A116566 A116567 * A116569 A116570 A116571


KEYWORD

nonn


AUTHOR

Roger L. Bagula, Mar 18 2006


EXTENSIONS

Edited by N. J. A. Sloane, Apr 05 2006


STATUS

approved



