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 A162144 Products of cubes of 3 distinct primes. 3
 27000, 74088, 287496, 343000, 474552, 1061208, 1157625, 1331000, 1481544, 2197000, 2628072, 3652264, 4492125, 4913000, 5268024, 6028568, 6434856, 6859000, 7414875, 10941048, 12167000, 12326391, 13481272, 14886936, 16581375, 17173512, 18821096 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Numbers of the form p^3*q^3*r^3 where p, q, r are three distinct primes. The cubic analog of A085986 (squares of 2 distinct primes). LINKS T. D. Noe, Table of n, a(n) for n = 1..1000 FORMULA a(n) = (A007304(n))^3. A000005(a(n)) = 64. Sum_{n>=1} 1/a(n) = (P(3)^3 + 2*P(9) - 3*P(3)*P(6))/6 = (A085541^3 + 2*A085969 - 3*A085541*A085966)/6 = 0.0000661486..., where P is the prime zeta function. - Amiram Eldar, Oct 30 2020 EXAMPLE 27000 = 2^3*3^3*5^3. 74088 = 2^3*3^3*7^3. 287496 = 2^3*3^3*11^3. MATHEMATICA fQ[n_]:=Last/@FactorInteger[n]=={1, 1, 1}; Select[Range[1000], fQ]^3 CROSSREFS Cf. A006881, A085986, A162142, A162143. Cf. A085541, A085966, A085969. Sequence in context: A249496 A227348 A176359 * A305728 A253485 A253480 Adjacent sequences:  A162141 A162142 A162143 * A162145 A162146 A162147 KEYWORD nonn AUTHOR Vladimir Joseph Stephan Orlovsky, Jun 25 2009 EXTENSIONS Edited by R. J. Mathar, Aug 14 2009 STATUS approved

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Last modified November 26 21:07 EST 2021. Contains 349344 sequences. (Running on oeis4.)