A220878 - OEIS

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A220878

Number of Catalan M-paths.

1, 2, 11, 75, 578, 4791, 41657, 374728, 3458073, 32553979, 311399612, 3018079529, 29573648337, 292494535982, 2916080902215, 29274765251531, 295683573477358, 3002574533715331, 30636334463337153, 313935121354840276, 3229378471937953501, 33336180648639258723

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,2

LINKS

Table of n, a(n) for n=0..21.

J. P. S. Kung and A. de Mier, Catalan lattice paths with rook, bishop and spider steps, Journal of Combinatorial Theory, Series A 120 (2013) 379-389.

FORMULA

Kung and de Mier give a g.f.

MAPLE

g := (3*t^2-t-1+sqrt(1-14*t+35*t^2-30*t^3+9*t^4))/4/t/(3*t-2) ;

taylor(%, t=0, 40) ;

seq(coeftayl(%, t=0, n), n=0..39) ; # R. J. Mathar, Jan 30 2013