OFFSET
1,1
EXAMPLE
a(1) = 6 is 1-semiprime equal 2*3;
a(2) = 1155 is 2-semiprime equal (3*5)*(7*11);
a(3) = 86822723 is 3-semiprime equal (11*13)*(17*19)*(23*29).
CROSSREFS
KEYWORD
nonn
AUTHOR
Giovanni Teofilatto, Jan 05 2006
STATUS
approved