The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 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 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. 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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

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