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

20, 1285, 39425, 971610, 21272810, 432363395, 8355404595

Offset

1,1

Links

Table of n, a(n) for n=1..7.

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 B(n, k):
    m = k * n
    s = 0
    for i in range(1, m):
        for j in range(i + 1, m + 1):
            s += A(i, j, n, k)
    return s
def A338961(n):
    return B(5, n)
print([A338961(n) for n in range(1, 6)])

Crossrefs

Cf. A003732, A338709, A338960, A338962, A338963.

Sequence in context: A174581 A153469 A160253 * A274645 A005982 A229476

Adjacent sequences: A338958 A338959 A338960 * A338962 A338963 A338964

Keyword

nonn,more

Author

Seiichi Manyama, Dec 18 2020

Status

approved