A127833 -id:A127833

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A127832

Array T by antidiagonals: for h>=0 and k>=0, T(h,k)=number of UR paths from (0,0) to (h,k) that touch the line y=2x/3 only at lattice points. A UR path is a path of steps of length 1 each directed up or right.

+10
1

0, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 3, 2, 2, 1, 1, 4, 5, 4, 3, 1, 1, 5, 9, 9, 7, 4, 1, 1, 6, 14, 18, 9, 11, 5, 1, 1, 7, 20, 32, 27, 11, 16, 6, 1, 1, 8, 27, 52, 59, 27, 27, 22, 7, 1, 1, 9, 35, 79, 111, 86, 54, 49, 29, 8, 1, 1, 10, 44, 114, 190, 197, 140, 103, 78, 37, 9, 1, 1, 11, 54, 158, 304, 387

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

OFFSET

1,8

LINKS

Table of n, a(n) for n=1..84.

EXAMPLE

Northwest corner:

0 1 1 1 1 1

1 1 2 3 4 5

1 1 2 5 9 14

1 2 4 9 18 32

1 3 7 9 27 59

The 4 UR paths for T(3,2) are RRRUU, RRURU, UURRR, URURR. These

paths touch the line y=2x/3 only at the lattice points (0,0) and (3,2).

CROSSREFS

Cf. A047110, A127833.

KEYWORD

nonn,tabl

AUTHOR

Clark Kimberling, Feb 01 2007

STATUS

approved

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