OFFSET
1,1
COMMENTS
Elements in this sequence can themselves be 3-almost primes. a(1) = 8 = 2^3. a(2) = 20 = 2^2 * 5. a(20) = 964 = 2^2 * 241. a(28) = 1825 = 5^2 * 73. a(30) = 2074 = 2 * 17 * 61. a(34) = 2637 = 3^2 * 293. a(40) = 3614 = 2 * 13 * 139. a(41) = 3786 = 2 * 3 * 631. a(45) = 4503 = 3 * 19 * 79. Does this happen infinitely often? - Jonathan Vos Post, Dec 11 2004
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..1000
FORMULA
a(n) = sum_{i=1..n} A014612(i). - R. J. Mathar, Sep 14 2012
EXAMPLE
a(2)=20 because sum of first two 3-almost primes i.e. 8+12 is 20.
MATHEMATICA
Accumulate[Select[Range[500], PrimeOmega[#]==3&]] (* Harvey P. Dale, Jan 17 2014 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Shyam Sunder Gupta, Aug 24 2003
STATUS
approved