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A271507 Number of self-avoiding walks of any length from NW to SW corners on a n X n grid or lattice. 10
1, 2, 11, 178, 8590, 1246850, 550254085, 741333619848, 3046540983075504, 38141694646516492843, 1453908228148524205711098, 168707605740228097581729005751, 59588304533380500951726150179910606, 64061403305026776755367065417308840021540 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..14.

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-Fran├žois 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.

Cf. A007764, A000532, A001184, A145157, A120443, A003763.

Sequence in context: A012953 A012974 A011839 * A217391 A297601 A089760

Adjacent sequences:  A271504 A271505 A271506 * A271508 A271509 A271510

KEYWORD

nonn

AUTHOR

Andrew Howroyd, Apr 08 2016

STATUS

approved

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Last modified April 21 13:23 EDT 2021. Contains 343153 sequences. (Running on oeis4.)