OFFSET
1,1
COMMENTS
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
KEYWORD
nonn
AUTHOR
Debapriyay Mukhopadhyay, Nov 27 2015
STATUS
approved