cp's OEIS Frontend

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

%I A339854 #28 Jun 29 2023 11:00:40
%S A339854 1,4,80,7104,3292184,6523266332,56203566442908,2176852129116199068,
%T A339854 373334515946952014204102,281931891850296665963970600460,
%U A339854 939652851372937937187518231503848142,13807942929878598929190143960742601141566220,893498265685263112931409501489577970162598024007690
%N A339854 Number of Hamiltonian circuits within parallelograms of size n X n on the triangular lattice.
%H A339854 Ed Wynn, <a href="/A339854/b339854.txt">Table of n, a(n) for n = 2..16</a>
%e A339854 a(2) = 1:
%e A339854     *---*
%e A339854    /   /
%e A339854   *---*
%e A339854 a(3) = 4:
%e A339854       *   *---*      *---*---*
%e A339854      / \ /   /        \     /
%e A339854     *   *   *      *---*   *
%e A339854    /       /      /       /
%e A339854   *---*---*      *---*---*
%e A339854       *---*---*      *---*---*
%e A339854      /       /      /       /
%e A339854     *   *   *      *   *---*
%e A339854    /   / \ /      /     \
%e A339854   *---*   *      *---*---*
%Y A339854 Main diagonal of A339849.
%Y A339854 Cf. A140519.
%K A339854 nonn
%O A339854 2,2
%A A339854 _Seiichi Manyama_, Dec 19 2020
%E A339854 More terms from _Ed Wynn_, Jun 28 2023