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%I #7 Mar 31 2012 10:32:24
%S 1,0,1,1,2,1,8,8,48,54,331,439,2558,3734,21057,33384,182293,307719,
%T 1638465,2913775,15181584,28194412,144206012,277887666,1398566992
%N Number of nonisomorphic ways a loop can cross three roads meeting in a Y n times (orbits under symmetry group of order 6).
%C There is no constraint on touching any particular sector.
%C The Mercedes-Benz problem: closed meanders crossing a Y.
%H Anonymous, <a href="/A078105/a078105.a.gif">Illustration for a(3) = 1</a>
%e With three crossings the loop must cut each road exactly once, so a(3) = 1.
%e With 4 crossings the loop can cut one road 4 times (one possibility), or two roads twice each (one possibility), so a(4) = 2.
%Y Cf. A078104 (total number of solutions), A077460 and A005315 (loop crossing one road).
%K nonn,nice
%O 0,5
%A _N. J. A. Sloane_ and _Jon Wild_, Dec 05 2002
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