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A338963 Number of (undirected) paths in C_n X P_n. 5
1209, 103184, 21272810, 11481159930 (list; graph; refs; listen; history; text; internal format)
OFFSET
3,1
COMMENTS
a(8) = 70244258770074672.
LINKS
PROG
(Python)
# Using graphillion
from graphillion import GraphSet
def make_CnXPk(n, k):
grids = []
for i in range(1, k + 1):
for j in range(1, n):
grids.append((i + (j - 1) * k, i + j * k))
grids.append((i + (n - 1) * k, i))
for i in range(1, k * n, k):
for j in range(1, k):
grids.append((i + j - 1, i + j))
return grids
def A(start, goal, n, k):
universe = make_CnXPk(n, k)
GraphSet.set_universe(universe)
paths = GraphSet.paths(start, goal)
return paths.len()
def A338963(n):
m = n * n
s = 0
for i in range(1, m):
for j in range(i + 1, m + 1):
s += A(i, j, n, n)
return s
print([A338963(n) for n in range(3, 7)])
CROSSREFS
Sequence in context: A279983 A187862 A186864 * A135239 A046043 A358538
KEYWORD
nonn,more
AUTHOR
Seiichi Manyama, Dec 18 2020
STATUS
approved

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Last modified July 15 10:24 EDT 2024. Contains 374332 sequences. (Running on oeis4.)