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A273487
Density of numbers without prime exponents in their factorization.
1
6, 5, 0, 4, 4, 5, 6, 0, 8, 4, 2, 1, 9, 1, 2, 6, 9, 1, 3, 9, 0, 4, 4, 4, 3, 6, 1, 1, 0, 4, 6, 5, 9, 6, 4, 5, 5, 7, 7, 0, 1, 0, 2, 9, 6, 9, 2, 2, 0, 5, 4, 9, 7, 6, 0, 2, 0, 1, 9, 3, 5, 8, 8, 5, 5, 5, 2, 3, 4, 2, 8, 6, 9, 1, 6, 8, 2, 1, 3, 6, 7, 7, 4, 9, 3
OFFSET
0,1
FORMULA
Prod_{p prime} 1 - (1 - 1/p)*Sum_{q prime} p^-q.
EXAMPLE
0.6504456084219126913904443611046...
MAPLE
eser := 1-x^2+x^4 ;
for pidx from 3 to 100 do
p := ithprime(pidx) ;
eser := eser -x^p+x^(p+1) ;
end do:
eser := taylor(eser, x=0, p) ;
gfun[seriestolist](eser) ;
subsop(1=NULL, %) ;
L := EULERi(%) ;
Digits := 180 ;
x := 1.0 ;
for i from 2 to nops(L) do
if op(i, L) <> 0 then
x := x*evalf(Zeta(i)^op(i, L)) ;
printf("%.70f\n", x) ;
fi ;
end do; # R. J. Mathar, Jul 11 2016
PROG
(PARI) leps=log(2)*(1-bitprecision(1.))
f(x)=my(s=0.); forprime(p=2, 1-leps/log(x), s+=x^-p); s
6/Pi^2*prodeuler(p=2, 1e6, (1-(1-1/p)*f(p))/(1-1/p^2))
CROSSREFS
Density of A274034.
Sequence in context: A010773 A099288 A256717 * A134103 A196621 A340443
KEYWORD
nonn,cons
AUTHOR
STATUS
approved