A175896 Number of lattice paths from (0,0) to (n,n) using steps S={(k,0),(0,k),(1,1)|0<k<=3} which never go above the line y-x.

1, 2, 9, 57, 396, 2948, 23016, 185838, 1539066, 13001677, 111600446, 970550862, 8533427593, 75728797781, 677427655798, 6102015206945, 55299451023428, 503847366381836, 4612663920303329, 42409513650507927, 391425863599784588

Offset

0,2

Links

Table of n, a(n) for n=0..20.

Crossrefs

Cf. A006318, A175895.

Sequence in context: A004103 A295775 A223381 * A175900 A175912 A218824

Adjacent sequences: A175893 A175894 A175895 * A175897 A175898 A175899

Keyword

nonn

Author

Eric Werley, Dec 05 2010

Status

approved