

A190512


Number of onesided nstep prudent walks, avoiding single west step only, i.e., two or more consecutive west steps are permitted.


1



1, 2, 5, 11, 24, 53, 117, 258, 569, 1255, 2768, 6105, 13465, 29698, 65501, 144467, 318632, 702765, 1549997, 3418626, 7540017, 16630031, 36678688, 80897393, 178424817, 393528322, 867954037, 1914332891, 4222194104, 9312342245, 20539017381, 45300228866
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OFFSET

0,2


LINKS



FORMULA

G.f.: (1+x^2)/(12*xx^3).


EXAMPLE

a(2)=5 since there are 5 such walks: WW, NN, EN, NE, EE.


PROG

(PARI) my(x='x+O('x^35)); Vec((1+x^2)/(12*xx^3)) \\ Michel Marcus, Jun 28 2021


CROSSREFS

Cf. A110513 (essentially a signed version).


KEYWORD

nonn,walk


AUTHOR



STATUS

approved



