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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
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
Sequence in context: A131494 A234804 A261941 * A035903 A251189 A269185
KEYWORD
nonn
AUTHOR
STATUS
approved

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Last modified July 14 02:38 EDT 2024. Contains 374291 sequences. (Running on oeis4.)