Memory effect in growing trees

We show that the structure of a growing tree preserves an information on the shape of an initial graph. For the exponential trees, evidence of this kind of memory is provided by means of the iterative equations, derived for the moments of the node–node distance distribution. Numerical calculations confirm the result and allow to extend the conclusion to the Barabási–Albert scale-free trees. The memory effect almost disappears, if subsequent nodes are connected to the network with more than one link