cp's OEIS Frontend

A335612 Number of sets (in the Hausdorff metric geometry) at each location between two sets defined by a complete bipartite graph K(3,n) (with n at least 3) missing two edges, where the removed edges are incident to the same vertex in the three point part.

%I A335612 #31 Jun 27 2023 11:16:58
%S A335612 32,344,2792,20720,148592,1050824,7387832,51811040,362965952,
%T A335612 2541627704,17793992072,124565738960,871983556112,6103955042984,
%U A335612 42727895751512,299095901612480,2093673205343072,14655718119568664,102590043883482152
%N A335612 Number of sets (in the Hausdorff metric geometry) at each location between two sets defined by a complete bipartite graph K(3,n) (with n at least 3) missing two edges, where the removed edges are incident to the same vertex in the three point part.
%C A335612 The Hausdorff metric defines a distance between sets. Using this distance we can define line segments with sets as endpoints. Create two sets from the vertices of the parts A and B (with |A| = 3) of a complete bipartite graph K(3,n) (with n at least 3) missing two edges, where the removed edges are incident to the same point in A. Points in the sets A and B that correspond to vertices that are connected by edges are the same Euclidean distance apart. This sequence gives the number of sets at each location on the line segment between the sets A and B.
%C A335612 Number of {0,1} 3 X n matrices (with n at least 3) with two fixed zero entries in the same row and no zero rows or columns.
%C A335612 Take a complete bipartite graph K(3,n) (with n at least 3) having parts A and B where |A| = 3. This sequence gives the number of edge covers of the graph obtained from this K(3,n) graph after removing two edges, where the two removed edges are incident to the same vertex in A.
%H A335612 Steven Schlicker, Roman Vasquez, and Rachel Wofford, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL26/Wofford/wofford4.html">Integer Sequences from Configurations in the Hausdorff Metric Geometry via Edge Covers of Bipartite Graphs</a>, J. Int. Seq. (2023) Vol. 26, Art. 23.6.6.
%H A335612 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (11,-31,21).
%F A335612 a(n) = 9*7^(n-2) - 11*3^(n-2) + 2.
%F A335612 From _Colin Barker_, Jul 17 2020: (Start)
%F A335612 G.f.: 8*x^3*(4 - x) / ((1 - x)*(1 - 3*x)*(1 - 7*x)).
%F A335612 a(n) = 11*a(n-1) - 31*a(n-2) + 21*a(n-3) for n>5.
%F A335612 (End)
%p A335612 a:= proc(n) 9*7^(n-2)-11*3^(n-2)+2 end proc: seq(a(n), n=3..21);
%o A335612 (PARI) Vec(8*x^3*(4 - x) / ((1 - x)*(1 - 3*x)*(1 - 7*x)) + O(x^25)) \\ _Colin Barker_, Jul 17 2020
%Y A335612 Sequences of segments from removing edges from bipartite graphs A335608-A335613, A337416-A337418, A340173-A340175, A340199-A340201, A340897-A340899, A342580, A342796, A342850, A340403-A340405, A340433-A340438, A341551-A341553, A342327-A342328, A343372-A343374, A343800. Polygonal chain sequences A152927, A152928, A152929, A152930, A152931, A152932, A152933, A152934, A152939. Number of {0,1} n X n matrices with no zero rows or columns A048291.
%K A335612 easy,nonn
%O A335612 3,1
%A A335612 _Steven Schlicker_, Jul 16 2020