Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #36 Oct 02 2014 07:26:11
%S 1,1,3,4,11,33,121,597,4017,35103,428081,6851591,153025577,4535779061,
%T 187380634552
%N Number of isomorphism classes of involutory abelian/medial quandles of order n.
%C Both names "abelian" and "medial" refer to the identity (xy)(uv)=(xu)(yv). A (left) quandle is involutory (aka symmetric, kei) if all (left) translations have order at most 2, i.e., x(xy)=y is satisfied.
%C Enumerates intersection of the classes enumerated in A165200, A178432.
%H P. Jedlička, A. Pilitowska, D. Stanovský, A. Zamojska-Dzienio, <a href="http://arxiv.org/abs/1409.8396">The structure of medial quandles</a>, arXiv:1409.8396 [math.GR], 2014.
%H David Stanovský, <a href="http://www.karlin.mff.cuni.cz/~stanovsk/quandles/">Calculating with quandles</a> GAP code to calculate the numbers.
%Y Cf. A165200, A178432.
%K nonn,hard
%O 1,3
%A _David Stanovsky_, Oct 01 2014