OFFSET
1,1
COMMENTS
3-almost prime analog of A085366 Semiprimes that are the sum of two positive cubes. The sum of two positive cubes cannot be prime.
LINKS
Giovanni Resta, Table of n, a(n) for n = 1..10000
FORMULA
EXAMPLE
a(1) = 28 = 2^2 * 7 = 1^3 + 3^3.
a(2) = 370 = 2 * 5 * 37 = 3^3 + 7^3.
a(3) = 539 = 7^2 * 11 = 2^3 + 8^3.
a(4) = 637 = 7^2 * 13 = 5^3 + 8^3.
a(5) = 730 = 2 * 5 * 73 = 1^3 + 9^3.
a(6) = 854 = 2 * 7 * 61 = 5^3 + 9^3.
a(7) = 1001 = 7 * 11 * 13 = 1^3 + 10^3.
PROG
(PARI) is(n)=bigomega(n)==3 && #select(v->min(v[1], v[2])>0, thue('x^3+1, n))>0 \\ Charles R Greathouse IV, Feb 05 2017
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Jonathan Vos Post, Sep 23 2006
EXTENSIONS
More terms from R. J. Mathar, Jan 27 2009
STATUS
approved