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A271507
Number of self-avoiding walks of any length from NW to SW corners on an n X n grid or lattice.
11
1, 2, 11, 178, 8590, 1246850, 550254085, 741333619848, 3046540983075504, 38141694646516492843, 1453908228148524205711098, 168707605740228097581729005751, 59588304533380500951726150179910606, 64061403305026776755367065417308840021540
OFFSET
1,2
MATHEMATICA
A271465 = Cases[Import["https://oeis.org/A271465/b271465.txt", "Table"], {_, _}][[All, 2]];
a[n_] := A271465[[2 n^2 - 2 n + 1]];
Table[a[n], {n, 1, 14}] (* Jean-François Alcover, Sep 23 2019 *)
PROG
(Python)
# Using graphillion
from graphillion import GraphSet
import graphillion.tutorial as tl
def A271507(n):
if n == 1: return 1
universe = tl.grid(n - 1, n - 1)
GraphSet.set_universe(universe)
start, goal = 1, n
paths = GraphSet.paths(start, goal)
return paths.len()
print([A271507(n) for n in range(1, 10)]) # Seiichi Manyama, Mar 21 2020
CROSSREFS
Main diagonal of A271465.
Sequence in context: A012953 A012974 A011839 * A217391 A297601 A089760
KEYWORD
nonn
AUTHOR
Andrew Howroyd, Apr 08 2016
STATUS
approved