OFFSET
0,2
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..500
PROG
(Python)
# Using graphillion
from graphillion import GraphSet
import graphillion.tutorial as tl
def A333685(n, k):
if n == 0 or k == 0: return 1
universe = tl.grid(2 * n, 2 * k)
GraphSet.set_universe(universe)
start, goal = 1, (2 * n + 1) * (2 * k + 1)
paths = GraphSet.paths(start, goal).including((start + goal) // 2)
return paths.len()
def A333689(n):
return A333685(n, 2)
print([A333689(n) for n in range(15)])
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Apr 02 2020
STATUS
approved