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 A175895 Number of lattice paths from (0,0) to (n,n) using steps S={(k,0),(0,k),(1,1)|0

%I

%S 1,2,9,50,314,2116,14949,109246,818978,6263072,48668366,383182648,

%T 3050196328,24506969724,198482172753,1618700191002,13281652367078,

%U 109564878995724,908171084052990,7560049450347964,63176859344766204

%N Number of lattice paths from (0,0) to (n,n) using steps S={(k,0),(0,k),(1,1)|0<k<=2} which never go above the line y=x.

%e a(2)=9 because we can reach (2,2) in the following ways:

%e (1,0),(1,0),(0,1),(0,1)

%e (1,0),(1,0),(0,2)

%e (2,0),(0,1),(0,1)

%e (2,0),(0,2)

%e (1,0),(1,1),(0,1)

%e (1,0),(0,1),(1,1)

%e (1,1),(1,0),(0,1)

%e (1,1),(0,1),(1,0)

%e (1,1)(1,1)

%Y Cf. A006318

%K nonn

%O 0,2

%A _Eric Werley_, Dec 05 2010

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Last modified September 22 09:47 EDT 2021. Contains 347606 sequences. (Running on oeis4.)