OFFSET
1,4
COMMENTS
A cycle and its reverse are not both counted.
We follow the convention in A003216 that the complete graphs on 1 and 2 nodes have 1 and 0 Hamiltonian cycles, respectively, so that a(1) = a(2) = 1 and a(3) = 0, but it could also be argued that a(1) = a(2) = 0 and/or a(3) = 1.
LINKS
Pontus von Brömssen, A Hamiltonian cycle in the heptomino graph.
Pontus von Brömssen, A Hamiltonian cycle in the hexomino graph.
MathOverflow, Generating all pentominoes by cutting and pasting.
FORMULA
a(n) <= A367123(n).
a(n) > 0 for 4 <= n <= 13.
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Pontus von Brömssen, Nov 18 2023
STATUS
approved