  Let $G$ be a finite simple graph on the vertex set $V(G)$ and let $r$ be a
positive integer. We consider the hypergraph $\mathrm{Con}_r(G)$ whose vertices
are the vertices of $G$ and the (hyper)edges are all $A\subseteq V(G)$ such
that $|A|=r+1$ and the induced subgraph $G[A]$ is connected. The (hyper)edge
ideal $I_r(G)$ of $\mathrm{Con}_r(G)$ is also the Stanley-Reisner ideal of a
generalisation of the independence complex of $G$, called the $r$-independence
complex $\mathrm{Ind}_r(G)$. In this article we make extensive use of the
Mayer-Vietoris sequence to find the graded Betti numbers of $I_r(G_1*G_2)$ in
terms of the graded Betti numbers of $I_r(G_1)$ and $I_r(G_2)$, where $G_1*G_2$
is the join of $G_1$ and $G_2$. Moreover, we find formulas for all the graded
Betti numbers of $I_r(G)$, when $G$ is a complete graph, complete multipartite
graph, cycle graph and the wheel graph.
