For a graph X, the leap eccentric connectivity index (LECI) is x∈V(X) d2(x, X)ε(x, X), where d2(x, X) is the 2-distance degree and ε(x, X) the eccentricity of x. We establish a lower and an upper bound for the LECI of X in terms of its order and the number of universal vertices, and identify the extremal graphs. We prove an upper bound on the index for trees of a given order and diameter, and determine the extremal trees. We also determine trees with maximum LECI among all trees of a given order.

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