

A151467


Number of walks within N^2 (the first quadrant of Z^2) starting at (0,0), ending on the vertical axis and consisting of n steps taken from {(1, 1), (1, 0), (1, 1), (0, 1), (1, 0), (1, 1)}


0



1, 0, 5, 5, 60, 143, 1026, 3666, 21645, 94376, 518078, 2496709, 13395620, 68061470, 364081314, 1906396512, 10243047235, 54647381651, 295593657670, 1597150643075, 8699338664954, 47443092772573, 260081606235808, 1428683475568373, 7876997150310977, 43524929450676109, 241181417275425104
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

0,3


LINKS

Table of n, a(n) for n=0..26.
M. BousquetMelou and M. Mishna, 2008. Walks with small steps in the quarter plane, ArXiv 0810.4387.


MATHEMATICA

aux[i_Integer, j_Integer, n_Integer] := Which[Min[i, j, n] < 0  Max[i, j] > n, 0, n == 0, KroneckerDelta[i, j, n], True, aux[i, j, n] = aux[1 + i, 1 + j, 1 + n] + aux[1 + i, j, 1 + n] + aux[i, 1 + j, 1 + n] + aux[1 + i, 1 + j, 1 + n] + aux[1 + i, j, 1 + n] + aux[1 + i, 1 + j, 1 + n]]; Table[Sum[aux[0, k, n], {k, 0, n}], {n, 0, 25}]


CROSSREFS

Sequence in context: A189749 A009390 A009334 * A241209 A171726 A129358
Adjacent sequences: A151464 A151465 A151466 * A151468 A151469 A151470


KEYWORD

nonn,walk


AUTHOR

Manuel Kauers, Nov 18 2008


STATUS

approved



