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 A001748 3 * primes. 31
 6, 9, 15, 21, 33, 39, 51, 57, 69, 87, 93, 111, 123, 129, 141, 159, 177, 183, 201, 213, 219, 237, 249, 267, 291, 303, 309, 321, 327, 339, 381, 393, 411, 417, 447, 453, 471, 489, 501, 519, 537, 543, 573, 579, 591, 597, 633, 669, 681, 687, 699, 717, 723, 753 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS A164023(a(n)) = A164024(a(n)) = A000040(n). - Reinhard Zumkeller, Aug 09 2009 Semiprimes of the form m*k such that m/(k-2)=prime. - Juri-Stepan Gerasimov, May 25 2010 The sum of two distinct terms from sequence A179545. - Odimar Fabeny, Aug 18 2010 Solutions of the differential equation n'=1/3*(n+9), where n' is the arithmetic derivative of n. - Paolo P. Lava, Feb 02 2012 A253046(a(n)) < a(n). - Reinhard Zumkeller, Dec 26 2014 LINKS Paolo P. Lava, Table of n, a(n) for n = 1..20000 Eric Weisstein's World of Mathematics, Skeleton FORMULA a(n) = 3*A000040(n). - Omar E. Pol, Jan 31 2012 MATHEMATICA Prime[Range[22]]*3 (* Vladimir Joseph Stephan Orlovsky, Apr 29 2008 *) PROG (PARI) 3*primes(22) \\ Charles R Greathouse IV, May 19, 2011 (MAGMA) [3*p: p in PrimesUpTo(300)]; // Vincenzo Librandi, Mar 26 2014 (Haskell) a001748 = (* 3) . a000040  -- Reinhard Zumkeller, Dec 26 2014 CROSSREFS Subsequence of A001358. Cf. A179545. - Odimar Fabeny, Aug 18 2010 Cf. A100484, A253046, A164023, A164024, A000040, A253046. Sequence in context: A164383 A316047 A168544 * A097426 A075278 A316048 Adjacent sequences:  A001745 A001746 A001747 * A001749 A001750 A001751 KEYWORD nonn,easy AUTHOR STATUS approved

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Last modified November 24 07:53 EST 2020. Contains 338607 sequences. (Running on oeis4.)