A339854 Number of Hamiltonian circuits within parallelograms of size n X n on the triangular lattice.

1, 4, 80, 7104, 3292184, 6523266332, 56203566442908, 2176852129116199068, 373334515946952014204102, 281931891850296665963970600460, 939652851372937937187518231503848142, 13807942929878598929190143960742601141566220, 893498265685263112931409501489577970162598024007690

Offset

2,2

Links

Ed Wynn, Table of n, a(n) for n = 2..16

Example

a(2) = 1:
    *---*
   /   /
  *---*
a(3) = 4:
      *   *---*      *---*---*
     / \ /   /        \     /
    *   *   *      *---*   *
   /       /      /       /
  *---*---*      *---*---*
      *---*---*      *---*---*
     /       /      /       /
    *   *   *      *   *---*
   /   / \ /      /     \
  *---*   *      *---*---*

Crossrefs

Main diagonal of A339849.

Cf. A140519.

Sequence in context: A156103 A204294 A203480 * A116189 A159063 A337053

Adjacent sequences: A339851 A339852 A339853 * A339855 A339856 A339857

Keyword

nonn

Author

Seiichi Manyama, Dec 19 2020

Extensions

More terms from Ed Wynn, Jun 28 2023

Status

approved