This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
The start of the sequence as table: 0 0 1 1 1 1 1 ... 0 1 3 6 5 8 7 ... 1 3 48 126 390 1014 2982 ... 1 6 126 1344 2930 28060 55230 ... 1 5 390 2930 23580 145210 1045940 ... 1 8 1014 28060 145210 3273360 16111928 ... 1 7 2982 55230 1045940 16111928 257165468 ... ...
Table[Length[FindCycle[GraphProduct[CycleGraph[n], CycleGraph[n], "Cartesian"], Infinity, All]], {n, 3, 5}] (* Eric W. Weisstein, Dec 16 2023 *)
# Using graphillion
from graphillion import GraphSet
def make_CnXCk(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))
grids.append((i + k - 1, i))
return grids
def A296527(n):
universe = make_CnXCk(n, n)
GraphSet.set_universe(universe)
cycles = GraphSet.cycles()
return cycles.len()
print([A296527(n) for n in range(3, 7)]) # Seiichi Manyama, Nov 22 2020
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