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A092871 Number of composites < 10^n. 2
0, 4, 73, 830, 8769, 90406, 921500, 9335419, 94238543, 949152464, 9544947487, 95881945185, 962392087980, 9653934463159, 96795058249196, 970155429577329, 9720761658966073, 97376442842345765, 975260045712259138, 9765942332723655391, 97779180397439081158 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

The number 1 is omitted from the count as it is neither prime nor composite

LINKS

Table of n, a(n) for n=0..20.

C. Caldwell, The Prime Pages, How many primes are there? Table 1. Values of pi(x).

FORMULA

For n>0, a(n) = A065894(n) - 1 = 10^n - 2 - A006880(n). - Max Alekseyev, Aug 15 2013

EXAMPLE

10^3=1000. 1000-2=998. a(3)=830 because the 830 composites+168 primes must total 998.

MATHEMATICA

Table[10^i-PrimePi[10^i]-2, {i, 14}] (* Harvey P. Dale, Oct 01 2011 *) (* Mathematica's implementation of PrimePi does not work for 10^15 or above *)

CROSSREFS

Cf. A065894, A006880, A092801, A092802.

Sequence in context: A055556 A168299 A089665 * A222767 A090212 A137046

Adjacent sequences:  A092868 A092869 A092870 * A092872 A092873 A092874

KEYWORD

nonn

AUTHOR

Enoch Haga, Mar 08 2004

EXTENSIONS

Edited by Max Alekseyev, Aug 15 2013

STATUS

approved

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Last modified May 10 22:16 EDT 2021. Contains 343780 sequences. (Running on oeis4.)