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A190464
Numbers with prime factorization p^4*q^6.
4
5184, 11664, 40000, 153664, 250000, 455625, 937024, 1265625, 1750329, 1827904, 1882384, 5345344, 8340544, 9529569, 10673289, 17909824, 20820969, 28344976, 37515625, 45265984, 59105344, 60886809, 73530625, 77228944, 95004009, 119946304, 143496441, 180848704, 204004089, 218803264
OFFSET
1,1
COMMENTS
A subsequence of A175745 (Numbers with 35 divisors).
First different term in A175745 is 17179869184(=2^34).
FORMULA
Sum_{n>=1} 1/a(n) = P(4)*P(6) - P(10) = A085964 * A085966 - P(10) = 0.000320..., where P is the prime zeta function. - Amiram Eldar, Jul 06 2020
MATHEMATICA
f[n_]:=Sort[Last/@FactorInteger[n]]=={4, 6}; Select[Range[50000000], f] (*and*) lst={}; Do[Do[If[n!=m, AppendTo[lst, Prime[n]^6*Prime[m]^4]], {n, 50}], {m, 50}]; Take[Union@lst, 50]
PROG
(PARI) list(lim)=my(v=List(), t); forprime(p=2, (lim\16)^(1/6), t=p^6; forprime(q=2, (lim\t)^(1/4), if(p==q, next); listput(v, t*q^4))); vecsort(Vec(v)) \\ Charles R Greathouse IV, Jul 24 2011
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved