

A190569


Number of nstep onesided prudent walks, avoiding single west steps and single east steps.


0



1, 1, 3, 7, 13, 25, 51, 103, 205, 409, 819, 1639, 3277, 6553, 13107, 26215, 52429, 104857, 209715, 419431, 838861, 1677721, 3355443, 6710887, 13421773, 26843545, 53687091, 107374183, 214748365, 429496729, 858993459, 1717986919, 3435973837
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OFFSET

0,3


LINKS



FORMULA

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


PROG

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


CROSSREFS

Essentially a duplicate of A007909.


KEYWORD

nonn,walk


AUTHOR



STATUS

approved



