A114297 First row of Modified Schroeder numbers for q=5 (A114293).

1, 1, 1, 2, 5, 13, 42, 150, 553, 2202, 9233, 39726, 176932, 810798, 3786137, 18022100, 87265298, 428202617, 2127088358, 10684752474, 54181245592, 277101480826, 1428262595206, 7412626391101, 38712130945272, 203330779196084

Offset

0,4

Comments

a(i) is the number of paths from (0,0) to (i,i) using steps of length (0,1), (1,0) and (1,1), not passing above the line y=x nor below the line y=2x/3.

References

C. Hanusa (2005). A Gessel-Viennot-Type Method for Cycle Systems with Applications to Aztec Pillows. PhD Thesis. University of Washington, Seattle, USA.

Links

Table of n, a(n) for n=0..25.

Example

The number of paths from (0,0) to (4,4) staying between the lines y=x and y=2x/3 using steps of length (0,1), (1,0) and (1,1) is a(4)=5.

Crossrefs

See also A112833-A112844 and A114292-A114299.

Sequence in context: A149872 A149873 A149874 * A178682 A229161 A192745

Adjacent sequences: A114294 A114295 A114296 * A114298 A114299 A114300

Keyword

nonn

Author

Christopher Hanusa (chanusa(AT)math.binghamton.edu), Nov 21 2005

Status

approved