

A091716


Standard deviation (rounded) of primes below 10^n.


2



2, 29, 298, 2962, 29412, 292821, 2921863, 29170821, 291324189, 2910238255, 29078387910, 290589147156, 2904276036695
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OFFSET

1,1


COMMENTS

It appears that a good estimate for the standard deviation of primes below 10^(n+1) is about 10 times the term for 10^n.
Heuristically, if we use a model where each positive integer x has probability approximately 1/log(x) of being prime, we should expect the standard deviation of the primes below N to be approximately N/sqrt(12).  Robert Israel, Sep 23 2014


REFERENCES

John E. Freund, Modern elementary statistics, 5th ed. (PrenticeHall, 1979), pp. 4247


LINKS

Table of n, a(n) for n=1..13.


EXAMPLE

a(6) = 292821 (rounded from 292820.634) because this is the computed and rounded sample standard deviation of the 78498 primes below 10^6.


MAPLE

seq(round(Statistics:StandardDeviation(select(isprime, [$2 .. 10^n1]))), n=1..7); # Robert Israel, Sep 23 2014


CROSSREFS

Cf. A092800, A092801, A092802.
Sequence in context: A101750 A160952 A088615 * A198698 A094940 A152274
Adjacent sequences: A091713 A091714 A091715 * A091717 A091718 A091719


KEYWORD

nonn,more


AUTHOR

Enoch Haga, Mar 05 2004


EXTENSIONS

a(9)a(13) from Hiroaki Yamanouchi, Sep 23 2014


STATUS

approved



