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A190465
Numbers with prime factorization p^5q^5.
5
7776, 100000, 537824, 759375, 4084101, 5153632, 11881376, 39135393, 45435424, 52521875, 79235168, 90224199, 205962976, 345025251, 503284375, 601692057, 656356768, 916132832, 1160290625, 1564031349, 2219006624, 2706784157, 3707398432
OFFSET
1,1
LINKS
FORMULA
Sum_{n>=1} 1/a(n) = (P(5)^2 - P(10))/2 = (A085965^2 - P(10))/2 = 0.000142..., where P is the prime zeta function. - Amiram Eldar, Jul 06 2020
MATHEMATICA
f[n_]:=Sort[Last/@FactorInteger[n]]=={1, 1}; Select[Range[10000], f]^5
PROG
(PARI) list(lim)=my(v=List(), t); forprime(p=2, lim^(1/10), t=p^5; forprime(q=p+1, (lim\t)^(1/5), listput(v, t*q^5))); vecsort(Vec(v)) \\ Charles R Greathouse IV, Jul 20 2011
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved