cp's OEIS Frontend

A338961 Number of (undirected) paths in C_5 X P_n.

%I A338961 #16 Dec 19 2020 08:05:17
%S A338961 20,1285,39425,971610,21272810,432363395,8355404595
%N A338961 Number of (undirected) paths in C_5 X P_n.
%o A338961 (Python)
%o A338961 # Using graphillion
%o A338961 from graphillion import GraphSet
%o A338961 def make_CnXPk(n, k):
%o A338961     grids = []
%o A338961     for i in range(1, k + 1):
%o A338961         for j in range(1, n):
%o A338961             grids.append((i + (j - 1) * k, i + j * k))
%o A338961         grids.append((i + (n - 1) * k, i))
%o A338961     for i in range(1, k * n, k):
%o A338961         for j in range(1, k):
%o A338961             grids.append((i + j - 1, i + j))
%o A338961     return grids
%o A338961 def A(start, goal, n, k):
%o A338961     universe = make_CnXPk(n, k)
%o A338961     GraphSet.set_universe(universe)
%o A338961     paths = GraphSet.paths(start, goal)
%o A338961     return paths.len()
%o A338961 def B(n, k):
%o A338961     m = k * n
%o A338961     s = 0
%o A338961     for i in range(1, m):
%o A338961         for j in range(i + 1, m + 1):
%o A338961             s += A(i, j, n, k)
%o A338961     return s
%o A338961 def A338961(n):
%o A338961     return B(5, n)
%o A338961 print([A338961(n) for n in range(1, 6)])
%Y A338961 Cf. A003732, A338709, A338960, A338962, A338963.
%K A338961 nonn,more
%O A338961 1,1
%A A338961 _Seiichi Manyama_, Dec 18 2020