A175935 Number of lattice paths from (0,0) to (n,n) using steps S={(k,0),(0,k),(r,r)|0<k<=2,0<r<=2} which never go above the line y=x.

1, 2, 10, 55, 351, 2401, 17248, 128221, 978082, 7612155, 60204488, 482481220, 3909460725, 31974923487, 263623879118, 2188682538746, 18282238300443, 153537981720402, 1295640515428649, 10980400434511117, 93418283866708579

Offset

0,2

Links

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

Crossrefs

Cf. A175934, A175936, A175937, A175939

Sequence in context: A330620 A268556 A371816 * A216721 A122826 A320129

Adjacent sequences: A175932 A175933 A175934 * A175936 A175937 A175938

Keyword

nonn

Author

Eric Werley, Dec 06 2010

Status

approved