A264887 Numbers in A007504 such that omega(a(n)) = Omega(a(n)) = 4.
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
Offset: 1
Keywords
Examples
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.
Links
- John Cerkan, Table of n, a(n) for n = 1..10000
Programs
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Mathematica
t = Accumulate@ Prime@ Range@ 600; Select[t, PrimeNu@ # == PrimeOmega@ # == 4 &] (* Michael De Vlieger, Nov 27 2015, after Zak Seidov at A007504 *)
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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
Comments