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 A189990 Numbers with prime factorization p^2*q^6. 8
 576, 1600, 2916, 3136, 7744, 10816, 18225, 18496, 23104, 33856, 35721, 53824, 61504, 62500, 87616, 88209, 107584, 118336, 123201, 140625, 141376, 179776, 210681, 222784, 238144, 263169, 287296, 322624, 341056, 385641, 399424, 440896, 470596 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS T. D. Noe, Table of n, a(n) for n = 1..1000 Will Nicholes, Prime Signatures FORMULA Sum_{n>=1} 1/a(n) = P(2)*P(6) - P(8) = A085548 * A085966 - A085968 = 0.003658..., where P is the prime zeta function. - Amiram Eldar, Jul 06 2020 MATHEMATICA f[n_]:=Sort[Last/@FactorInteger[n]]=={2, 6}; Select[Range[800000], f] PROG (PARI) list(lim)=my(v=List(), t); forprime(p=2, (lim\4)^(1/6), t=p^6; forprime(q=2, sqrt(lim\t), if(p==q, next); listput(v, t*q^2))); vecsort(Vec(v)) \\ Charles R Greathouse IV, Jul 24 2011 CROSSREFS Subsequence of A137484. Cf. A179645, A179664. Cf. A085548, A085966, A085968. Sequence in context: A268773 A250789 A137484 * A064254 A281242 A067225 Adjacent sequences:  A189987 A189988 A189989 * A189991 A189992 A189993 KEYWORD nonn AUTHOR Vladimir Joseph Stephan Orlovsky, May 03 2011 STATUS approved

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Last modified May 18 07:01 EDT 2021. Contains 343994 sequences. (Running on oeis4.)