Sums of Squares and Products of Jacobsthal Numbers

Abstract

We consider sums of squares of odd and even terms of the Jacobsthal sequence and sums of their products. We also study the analogous alternating sums. These sums are related to products of appropriate Jacobsthal numbers and several integer sequences. The formulas that we discover show that a certain translation property for these sums holds, so that in practice, only sums of initial values and the information where the summation begins are necessary. 1