OFFSET
1,2
LINKS
Seiichi Manyama, Table of n, a(n) for n = 1..500
Eric Weisstein's World of Mathematics, Graph Cycle
FORMULA
Empirical g.f.: -x*(1 + 63*x - 418*x^2 + 287*x^3 + 840*x^4 + 1721*x^5 - 2540*x^6 + 3001*x^7 - 1149*x^8 - 544*x^9 + 90*x^10) / ((-1 + x)^2 * (-1 + 29*x - 136*x^2 + 55*x^3 + 190*x^4 + 645*x^5 - 626*x^6 + 953*x^7 - 409*x^8 - 178*x^9 + 30*x^10)). - Vaclav Kotesovec, Dec 09 2020
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 A339143(n):
universe = make_CnXPk(6, n)
GraphSet.set_universe(universe)
cycles = GraphSet.cycles()
return cycles.len()
print([A339143(n) for n in range(1, 20)])
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Nov 25 2020
STATUS
approved