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 A264887 Numbers in A007504 such that omega(a(n)) = Omega(a(n)) = 4. 2
 5830, 6870, 13490, 16401, 58406, 60146, 61910, 65534, 75130, 136114, 148827, 153178, 213538, 257358, 269074, 273054, 327198, 354102, 377310, 382038, 403611, 443685, 475323, 488774, 496905, 665130, 684510, 691026, 799846, 817563 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Omega and omega are given in A001221 and A001222, respectively. The corresponding numbers of prime summands, k(n), are 53, 57, 77, 84, 149, 151, 153, 157, 167, 219, 228, 231, 269, 293, 299, 301, 327, 339, 349, 351, 360, 376, 388, 393, 396, 453, 459, 461, 493, 498, ... Intersection of A007504 and A046386 (products of four distinct primes). - Michel Marcus, Dec 15 2015 LINKS John Cerkan, Table of n, a(n) for n = 1..10000 EXAMPLE For n = 1, k(n) = 53 and a(n) = A007504(53) = 5830 = 2*5*11*53. For n = 2, k(n) = 57 and a(n) = A007504(57) = 6870 = 2*3*5*229. For n = 3, k(n) = 77 and a(n) = A007504(77) = 13490 = 2*5*19*71. For n = 4, k(n) = 84 and a(n) = A007504(84) = 16401 = 3*7*11*71. For n = 5, k(n) = 149 and a(n) = A007504(149) = 58406 = 2*19*29*53. For n = 6, k(n) = 151 and a(n) = A007504(151) = 60146 = 2*17*29*61. Note that for each of the elements of the sequence, omega(a(n)) = Omega(a(n)) = 4, i.e., the number of prime factors of a(n) = the number of distinct prime factors of a(n) = 4. MATHEMATICA t = Accumulate@ Prime@ Range@ 600; Select[t, PrimeNu@ # == PrimeOmega@ # == 4 &] (* Michael De Vlieger, Nov 27 2015, after Zak Seidov at A007504 *) PROG (PARI) lista(nn) = {my(s = 0); for (n=1, nn, s += prime(n); if ((omega(s) == 4) && (bigomega(s)==4), print1(s, ", ")); ); } \\ Michel Marcus, Nov 28 2015 CROSSREFS Cf. A001221, A001222, A007504, A013918, A046386, A189072, A264885. Sequence in context: A131494 A234804 A261941 * A251189 A269185 A147859 Adjacent sequences:  A264884 A264885 A264886 * A264888 A264889 A264890 KEYWORD nonn AUTHOR Debapriyay Mukhopadhyay, Nov 27 2015 STATUS approved

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Last modified April 18 06:48 EDT 2019. Contains 322209 sequences. (Running on oeis4.)