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A076020 Number of systems with n elements having with one binary operation satisfying the equation B(AB)=A (semisymmetric quasigroups). This gives numbers of systems which are isomorphic to their transpose but are noncommutative. 1
0, 0, 0, 1, 3, 6, 24, 178, 1328 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

LINKS

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

CROSSREFS

Cf. A076016-A076021.

Sequence in context: A294381 A081072 A000717 * A018994 A018964 A304186

Adjacent sequences:  A076017 A076018 A076019 * A076021 A076022 A076023

KEYWORD

nonn,hard,more

AUTHOR

Richard C. Schroeppel, Oct 29 2002

STATUS

approved

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Last modified September 29 18:27 EDT 2020. Contains 337432 sequences. (Running on oeis4.)