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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. 2
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..27.

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

FORMULA

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

CROSSREFS

Cf. A046170.

Sequence in context: A148294 A148295 A288540 * A022854 A116409 A279196

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

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Last modified June 18 07:06 EDT 2019. Contains 324203 sequences. (Running on oeis4.)