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 A030078 Cubes of primes. 170
 8, 27, 125, 343, 1331, 2197, 4913, 6859, 12167, 24389, 29791, 50653, 68921, 79507, 103823, 148877, 205379, 226981, 300763, 357911, 389017, 493039, 571787, 704969, 912673, 1030301, 1092727, 1225043, 1295029, 1442897, 2048383, 2248091, 2571353, 2685619, 3307949 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Numbers with exactly three factorizations: A001055(a(n)) = 3 (e.g., a(4) = 1*343 = 7*49 = 7*7*7). - Reinhard Zumkeller, Dec 29 2001 Solutions of the equation n'=3*n^(2/3), where n' is the arithmetic derivative of n. - Paolo P. Lava, Oct 31 2012 Intersection of A014612 and A000578. Intersection of A014612 and A030513. - Wesley Ivan Hurt, Sep 10 2013 Let r(n) = (a(n)-1)/(a(n)+1)) if a(n) mod 4 = 1, (a(n)+1)/(a(n)-1)) otherwise; then Product_{n>=1} r(n) = (9/7) * (28/26) * (124/126) * (344/342) * (1332/1330) * ... = 48/35. - Dimitris Valianatos, Mar 06 2020 There exist 5 groups of order p^3, when p prime, so this is a subsequence of A054397. Three of them are abelian: C_p^3, C_p^2 X C_p and C_p X C_p X C_p = (C_p)^3. For 8 = 2^3, the 2 nonabelian groups are D_8 and Q_8; for odd prime p, the 2 nonabelian groups are (C_p x C_p) : C_p, and C_p^2 : C_p (remark, for p = 2, these two semi-direct products are isomorphic to D_8). Here C, D, Q mean Cyclic, Dihedral, Quaternion groups of the stated order; the symbols X and : mean direct and semidirect products respectively. - Bernard Schott, Dec 11 2021 REFERENCES Edmund Landau, Elementary Number Theory, translation by Jacob E. Goodman of Elementare Zahlentheorie (Vol. I_1 (1927) of Vorlesungen über Zahlentheorie), by Edmund Landau, with added exercises by Paul T. Bateman and E. E. Kohlbecker, Chelsea Publishing Co., New York, 1958, pp. 31-32. LINKS T. D. Noe, Table of n, a(n) for n = 1..1000 Xavier Gourdon and Pascal Sebah, Some Constants from Number theory. Eric Weisstein's World of Mathematics, Prime Power. Wikipedia, p-group, Classification. Index to sequences related to prime signature FORMULA n such that A062799(n) = 3. - Benoit Cloitre, Apr 06 2002 a(n) = A000040(n)^3. - Omar E. Pol, Jul 27 2009 A064380(a(n)) = A000010(a(n)). - Vladimir Shevelev, Apr 19 2010 A003415(a(n)) = A079705(n). - Reinhard Zumkeller, Jun 26 2011 A056595(a(n)) = 2. - Reinhard Zumkeller, Aug 15 2011 A000005(a(n)) = 4. - Wesley Ivan Hurt, Sep 10 2013 a(n) = A119959(n) * A008864(n) -1.- R. J. Mathar, Aug 13 2019 Sum_{n>=1} 1/a(n) = P(3) = 0.1747626392... (A085541). - Amiram Eldar, Jul 27 2020 From Amiram Eldar, Jan 23 2021: (Start) Product_{n>=1} (1 + 1/a(n)) = zeta(3)/zeta(6) (A157289). Product_{n>=1} (1 - 1/a(n)) = 1/zeta(3) (A088453). (End) EXAMPLE a(3) = 125; since the 3rd prime is 5, a(3) = 5^3 = 125. MATHEMATICA Array[Prime[ # ]^3&, 5! ] (* Vladimir Joseph Stephan Orlovsky, Sep 01 2008 *) PROG (Sage) [p**3 for p in prime_range(100)] # Zerinvary Lajos, May 15 2007 (Haskell) a030078 = a000578 . a000040 a030078_list = map a000578 a000040_list -- Reinhard Zumkeller, May 26 2012 (PARI) a(n)=prime(n)^3 \\ Charles R Greathouse IV, Mar 20 2013 (Magma) [p^3: p in PrimesUpTo(300)]; // Vincenzo Librandi, Mar 27 2014 (Python) from sympy import prime, primerange def aupton(terms): return [p**3 for p in primerange(1, prime(terms)+1)] print(aupton(35)) # Michael S. Branicky, Aug 27 2021 CROSSREFS Other sequences that are k-th powers of primes are: A000040 (k=1), A001248 (k=2), this sequence (k=3), A030514 (k=4), A050997 (k=5), A030516 (k=6), A092759 (k=7), A179645 (k=8), A179665 (k=9), A030629 (k=10), A079395 (k=11), A030631 (k=12), A138031 (k=13), A030635 (k=16), A138032 (k=17), A030637 (k=18). Cf. A060800, A131991, A000578, subsequence of A046099. Subsequence of A007422 and of A054397. Cf. A036966, A085541, A088453, A157289, A258600. Sequence in context: A240859 A277047 A046452 * A051751 A133042 A181361 Adjacent sequences: A030075 A030076 A030077 * A030079 A030080 A030081 KEYWORD nonn,easy AUTHOR Patrick De Geest STATUS approved

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Last modified December 2 06:12 EST 2023. Contains 367508 sequences. (Running on oeis4.)