OFFSET
0,2
COMMENTS
This is to A000679 as semigroups are to groups.
EXAMPLE
a(3) = 3684030417 because there are 3684030417 nonisomorphic semigroups of order 2^3 = 8.
CROSSREFS
KEYWORD
nonn,hard
AUTHOR
Jonathan Vos Post, Mar 08 2012
STATUS
approved