|
| |
|
|
A151445
|
|
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), (0, 1), (1, -1), (1, 0), (1, 1)}
|
|
0
| |
|
|
1, 1, 2, 6, 16, 49, 165, 538, 1881, 6673, 23954, 87931, 326739, 1224662, 4649697, 17778696, 68513483, 265907818, 1038089219, 4074688736, 16076107171, 63703583554, 253492204031, 1012528480799, 4058431546038, 16319598817463, 65820404923113, 266202737052052, 1079421216584541, 4387508855164279
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 0,3
|
|
|
LINKS
| M. Bousquet-Melou 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[-1 + i, 1 + j, -1 + n] + aux[i, -1 + 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: A052890 A052814 A192401 * A195645 A000136 A013989
Adjacent sequences: A151442 A151443 A151444 * A151446 A151447 A151448
|
|
|
KEYWORD
| nonn,walk
|
|
|
AUTHOR
| Manuel Kauers (manuel(AT)kauers.de), Nov 18 2008
|
| |
|
|
