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 A179702 Numbers of the form p^4*q^5 where p and q are two distinct primes. 2
 2592, 3888, 20000, 50000, 76832, 151875, 253125, 268912, 468512, 583443, 913952, 1361367, 2576816, 2672672, 3557763, 4170272, 5940688, 6940323, 7503125, 8954912, 10504375, 13045131, 20295603, 22632992, 22717712, 29552672, 30074733 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Subsequence of A046312 and of A137493. - R. J. Mathar, Jul 27 2010 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(4)*P(5) - P(9) = A085964 * A085965 - A085969 = 0.000748..., where P is the prime zeta function. - Amiram Eldar, Jul 06 2020 MATHEMATICA fQ[n_] := Sort[Last /@ FactorInteger @n] == {4, 5}; Select[ Range@ 31668000, fQ] (* fixed by Robert G. Wilson v, Aug 26 2010 *) lst = {}; Do[ If[p != q, AppendTo[lst, Prime@p^4*Prime@q^5]], {p, 12}, {q, 10}]; Take[ Sort@ Flatten@ lst, 27] (* Robert G. Wilson v, Aug 26 2010 *) Take[Union[First[#]^4 Last[#]^5&/@Flatten[Permutations/@Subsets[ Prime[ Range[30]], {2}], 1]], 30] (* Harvey P. Dale, Jan 01 2012 *) PROG (PARI) list(lim)=my(v=List(), t); forprime(p=2, (lim\16)^(1/5), t=p^5; forprime(q=2, (lim\t)^(1/4), if(p==q, next); listput(v, t*q^4))); vecsort(Vec(v)) \\ Charles R Greathouse IV, Jul 20 2011 CROSSREFS Cf. A006881, A007304, A065036, A085986, A085987, A092759, A178739, A179642, A179643, A179644, A179645, A179646, A179664, A179665, A179666, A179667, A179668, A179669, A179670, A179671, A179672, A179688, A179689, A179690, A179691, A179692, A179693, A179694, A179695, A179696, A179698, A179699, A179700. Cf. A085964, A085965, A085969. Sequence in context: A250241 A252152 A035894 * A258728 A326747 A156322 Adjacent sequences:  A179699 A179700 A179701 * A179703 A179704 A179705 KEYWORD nonn AUTHOR Vladimir Joseph Stephan Orlovsky, Jul 24 2010 EXTENSIONS Edited and extended by Ray Chandler and R. J. Mathar, Jul 26 2010 STATUS approved

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Last modified May 27 08:12 EDT 2022. Contains 354096 sequences. (Running on oeis4.)