The Narumi–Katayama index of a graph G is equal to the product of the degrees of the vertices of G. In this paper we consider a new version of the Narumi– Katayama index in which each vertex degree d is multiplied d times. We characterize the graphs extremal w.r.t. this new topological index.

The Narumi-Katayama index was the first topological index defined by the product of some graph theoretical quantities. Let G be a simple graph with vertex set V = {v1, . . . , vn} and d(v) be the degree of vertex v in the graph G. The Narumi-Katayama index is defined as NK(G) = ∏ v∈V d(v). In this paper, the Narumi-Katayama index is generalized using a n-vector x and it is denoted by GNK(G, x) ...

The Narumi-Katayama index of a graph was introduced in 1984 for representing the carbon skeleton of a saturated hydrocarbons and is defined as the product of degrees of all the vertices of the graph. In this paper, we examine the Narumi-Katayama index of different total transformation graphs. MSC (2010): Primary: 05C35; Secondary: 05C07, 05C40

‎    The Narumi-Katayama index is the first topological index defined by the product of some graph theoretical quantities. Let G be a simple graph. Narumi-Katayama index of G is defined as the product of the degrees of the vertices of G. In this paper, we define the Narumi-Katayama polynomial of G. Next, we investigate some properties of this polynomial for graphs and then, we obtain ...

Taiki Ogasa, Yuki Nakagawa, Shuji Isotani, Kenta Futamura, Manabu Okada, Takahisa Hiramitsu, Norihiko Goto, Shunji Narumi, Yoshihiko Watarai. Korean J Transplant 2022;36:281. https://doi.org/10.4285/ATW2022.F-4242

‎the narumi-katayama index was the first topological index defined‎ ‎by the product of some graph theoretical quantities‎. ‎let $g$ be a ‎simple graph with vertex set $v = {v_1,ldots‎, ‎v_n }$ and $d(v)$ be‎ ‎the degree of vertex $v$ in the graph $g$‎. ‎the narumi-katayama ‎index is defined as $nk(g) = prod_{vin v}d(v)$‎. ‎in this paper,‎ ‎the narumi-katayama index is generalized using a $n$-ve...