OFFSET
1,1
EXAMPLE
a(2) - a(1) = 5 - 2 = 3, which is prime (a "1-almost prime");
a(3) - a(2) = 11 - 5 = 6 = 2*3, which is semiprime (2-almost prime).
CROSSREFS
KEYWORD
nonn
AUTHOR
Zak Seidov, Nov 16 2016
EXTENSIONS
a(32)-a(33) from Jinyuan Wang, Jul 31 2021
STATUS
approved