%I A046171
%S A046171 1,2,5,13,36,98,272,740,2034,5513,15037,40617,110188,296806,802075,
%T A046171 2155667,5808335,15582342,41889578,112212146,301100754,805570061,
%U A046171 2158326727,5768299665,15435169364,41214098278,110164686454
%N A046171 Number of inequivalent self-avoiding walks of length n on a 2-D lattice 
               which start at origin, take first step in {+1,0} direction and if 
               any steps are vertical, a step up is taken before a step down.
%H A046171 Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/
               Self-AvoidingWalk.html">Link to a section of The World of Mathematics.</
               a>
%F A046171 a(n) = (A001411(n)+4)/8
%Y A046171 Cf. A046170.
%Y A046171 Sequence in context: A148293 A148294 A148295 this_sequence A022854 A116409 
               A002844
%Y A046171 Adjacent sequences: A046168 A046169 A046170 this_sequence A046172 A046173 
               A046174
%K A046171 nonn,walk,easy,nice
%O A046171 1,2
%A A046171 Eric Weisstein (eric(AT)weisstein.com)
%E A046171 More terms from Stephen A. Silver (maths(AT)argentum.freeserve.co.uk)