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%I #11 Aug 03 2020 03:42:35
%S 1,0,1,1,2,6,17,49,156,520,1762,6110,21713,78469,287393,1065951,
%T 3998286,15140500,57817817,222478829,861952579,3360043843,13171307962
%N Number of self-avoiding cycles of length 2n on the half-Manhattan lattice.
%C In the half-Manhattan lattice, E-W streets run alternately E and W, but N-S streets are two way.
%H Sean A. Irvine, <a href="https://github.com/archmageirvine/joeis/blob/master/src/irvine/oeis/a336/A336742.java">Java program</a> (github)
%Y Cf. A336724 (self-avoiding walks), A006781 (Manhattan lattice), A006782 (L-lattice), A002931 (square lattice).
%K nonn,walk,more
%O 0,5
%A _Sean A. Irvine_, Aug 02 2020