A339119 - OEIS

%I #16 Nov 24 2020 12:22:43

%S 21,681,23984,692194,18438929,487150371,12947640143,345142437669,

%T 9203308475041,245355064111139,6540331954247241,174341025325354201,

%U 4647322411026104632,123881845810609904802,3302270967098053652763,88027348826922694314763,2346510376337057464408514

%N Number of cycles in the grid graph P_7 X P_n.

%C a(n+1) / a(n) tends to 26.65660630533835653493851570574867751479178653672292060740586256111131858... - _Vaclav Kotesovec_, Nov 24 2020

%H Seiichi Manyama, <a href="/A339119/b339119.txt">Table of n, a(n) for n = 2..500</a>

%H Vaclav Kotesovec, <a href="/A339119/a339119.txt">Empirical g.f.</a>

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/GraphCycle.html">Graph Cycle</a>

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/GridGraph.html">Grid Graph</a>

%o (Python)

%o # Using graphillion

%o from graphillion import GraphSet

%o import graphillion.tutorial as tl

%o def A(n, k):

%o     universe = tl.grid(n - 1, k - 1)

%o     GraphSet.set_universe(universe)

%o     cycles = GraphSet.cycles()

%o     return cycles.len()

%o def A339119(n):

%o     return A(n, 7)

%o print([A339119(n) for n in range(2, 15)])

%Y Cf. A140517, A231829.

%K nonn

%O 2,1

%A _Seiichi Manyama_, Nov 24 2020