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.

1, 2, 5, 13, 36, 98, 272, 740, 2034, 5513, 15037, 40617, 110188, 296806, 802075, 2155667, 5808335, 15582342, 41889578, 112212146, 301100754, 805570061, 2158326727, 5768299665, 15435169364, 41214098278, 110164686454, 293922322781, 784924528667, 2092744741919, 5584227078870

Offset

1,2

Links

Table of n, a(n) for n=1..31.

Eric Weisstein's World of Mathematics, Self-Avoiding Walk.

Formula

a(n) = (A001411(n)+4)/8.

Crossrefs

Cf. A001411, A046170.

Sequence in context: A288540 A327014 A331030 * A022854 A356697 A346738

Adjacent sequences: A046168 A046169 A046170 * A046172 A046173 A046174

Keyword

nonn,walk,easy,nice

Author

Eric W. Weisstein

Extensions

More terms from Stephen A. Silver

Status

approved