1,2

H. Juergensen and P. Wick, Die Halbgruppen von Ordnungen <= 7, Semigroup Forum, 14 (1977), 69-79.

R. J. Plemmons, There are 15973 semigroups of order 6, Math. Algor., 2 (1967), 2-17; 3 (1968), 23.

Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.

Index entries for sequences related to semigroups

Column 1 of A058123.

Adjacent sequences: A002783 A002784 A002785 this_sequence A002787 A002788 A002789

Sequence in context: A089126 A113346 A054926 this_sequence A039719 A014466 A108799

nonn,nice,hard

N. J. A. Sloane (njas(AT)research.att.com).