The heptagon-wheel cocycle in the Kontsevich graph complex

The real vector space of non-oriented graphs is known to carry a differential graded Lie algebra structure. Cocycles in the Kontsevich graph complex, expressed using formal sums on $n$ vertices and $2n-2$ edges, induce -- under orientation mapping infinitesimal symmetries classical Poisson structures arbitrary finite-dimensional affine manifolds. Willwacher has stated existence nontrivial cocycle that contains $(2\ell+1)$-wheel with nonzero coefficient at every $\ell\in\mathbb{N}$. We present detailed calculations graphs; for tetrahedron pentagon-wheel cocycles, consisting $\ell = 1$ 2$ one two respectively, condition $d(\gamma) 0$ verified by hand. For next, heptagon-wheel (known exist 3$), we provide an explicit representative: it consists 46 8 14 edges.