A076018 Number of systems with n elements with one binary operation satisfying the equation B(AB)=A (semisymmetric quasigroups). Isomorphic systems and systems differing by a transposition have been omitted.

1, 1, 2, 3, 4, 9, 34, 393, 13980

Offset

1,3

Links

Table of n, a(n) for n=1..9.

Crossrefs

Cf. A076016-A076021.

Sequence in context: A245930 A086432 A186928 * A076017 A245366 A135112

Adjacent sequences: A076015 A076016 A076017 * A076019 A076020 A076021

Keyword

nonn,hard,more

Author

Richard C. Schroeppel, Oct 29 2002

Status

approved