# How many Hamiltonians Paths there are in almost regular graph ?

Let be $G=(V,E)$, where $V=\{1,\ldots,n\}$ and $E=\{\{i,j\}\subset V;|i-j|\leq k\}$ and $k<n$.
For which values of $k\geq 2$, can we count explicitly the number of Hamiltonian paths in $G$ ?

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S. Kitaev defines Path schemes $P(n,M)$ as graphs with vertex set $\{1,2,\dots,n\}$ and edges $(i,j)$ iff $|i-j|\in M$. Hamiltonian graphs on path schemes were mentioned in "On uniquely k-determined permutations" by S. Avgustinovich and S. Kitaev. The formula is not simple even in the case where $M=\{1,2\}$ (here), but I guess it depends on what kind of formula you are looking for.

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Hi Gjergji, thank you very much for the reply. The special case $M={1,2}$ is the most important for me right now. –  Leandro Jun 18 '10 at 22:02
Explicit values for $k\leq 9$ and small $n$ are given in the OEIS: