A201162 Irregular triangle read by rows: number of rank 2 Catalan paths of length n and area k.

1, 1, 1, 1, 1, 3, 4, 3, 1, 1, 1, 3, 6, 9, 12, 15, 18, 19, 18, 12, 5, 1, 1, 1, 3, 6, 11, 16, 25, 35, 48, 62, 77, 93, 111, 124, 133, 134, 127, 111, 85, 53, 24, 7, 1

Offset

0,6

Links

Table of n, a(n) for n=0..44.

Brian Drake, Limits of areas under lattice paths, Discrete Math. 309 (2009), no. 12, 3936-3953. See Section 5.

Example

Triangle begins
1
1 1
1 1 3 4 3 1
1 1 3 6 9 12 15 18 19 18 12 5 1
1 1 3 6 11 16 25 35 48 62 77 93 111 124 133 134 127 111 85 53 24 7 1
...

Crossrefs

Sequence in context: A078070 A254745 A111028 * A096646 A306234 A290057

Adjacent sequences: A201159 A201160 A201161 * A201163 A201164 A201165

Keyword

nonn,tabf,more

Author

N. J. A. Sloane, Nov 27 2011

Status

approved