The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A225877 Number of (2n-1)-step self-avoiding paths between two adjacent sites of a 2-dimensional square lattice. 1
 1, 2, 6, 28, 140, 744, 4116, 23504, 137412, 818260, 4945292, 30255240, 187009888, 1166065936, 7325767920, 46326922560, 294658864188, 1883761686216, 12098003064296, 78015400052920, 504955502402148, 3279315915221192, 21361995729759184, 139545638718942960 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS For n > 1, a(n) = A010566(n)/4: every self-avoiding open path from P to an adjacent site Q (except the one for n = 1) can be completed to a self-avoiding closed path by adding an edge from Q back to P, and exactly 1/4 of all closed paths through P contain that edge. LINKS Felix A. Pahl, Table of n, a(n) for n = 1..55 FORMULA For n>1, a(n) = n*A002931(n) = A010566(n)/4. MATHEMATICA A002931 = Cases[Import["https://oeis.org/A002931/b002931.txt", "Table"], {_, _}][[All, 2]]; a[n_] := n A002931[[n]]; a /@ Range[55] (* Jean-François Alcover, Jan 11 2020 *) CROSSREFS Sequence in context: A065577 A227294 A302336 * A350524 A228842 A218941 Adjacent sequences:  A225874 A225875 A225876 * A225878 A225879 A225880 KEYWORD nonn AUTHOR Felix A. Pahl, May 19 2013 STATUS approved

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

Last modified July 1 12:23 EDT 2022. Contains 354973 sequences. (Running on oeis4.)