A180907 Number of sequences of n integers p(i) i=0..n-1 with 0<=p(i)<=2*i and -2<p(i)-p(i-1)<=2

1, 3, 11, 42, 163, 639, 2520, 9976, 39595, 157441, 626859, 2498318, 9964308, 39764292, 158756360, 634044576, 2532959099, 10121210373, 40449588625, 161680869046, 646330342699, 2584001013295, 10331554755044, 41311180250504

Offset

1,2

Comments

Paths down a n-high staggered-grid minimally right-leaning right triangle with interior neighbor fanout 2*2.

Links

R. H. Hardin, Table of n, a(n) for n=1..100

M. Wallner, Lattice Path Combinatorics, Diplomarbeit, Institut für Diskrete Mathematik und Geometrie der Technischen Universität Wien, 2013.

Crossrefs

Column 2 of A180915.

Sequence in context: A122368 A344191 A032443 * A143464 A270561 A259858

Adjacent sequences: A180904 A180905 A180906 * A180908 A180909 A180910

Keyword

nonn

Author

R. H. Hardin Sep 23 2010

Status

approved