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A339854 Number of Hamiltonian circuits within parallelograms of size n X n on the triangular lattice. 1
1, 4, 80, 7104, 3292184, 6523266332, 56203566442908, 2176852129116199068, 373334515946952014204102, 281931891850296665963970600460 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,2

LINKS

Table of n, a(n) for n=2..11.

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,more

AUTHOR

Seiichi Manyama, Dec 19 2020

STATUS

approved

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Last modified September 25 03:12 EDT 2022. Contains 356953 sequences. (Running on oeis4.)