Break the 60 term series up into the sum of the 30 term series of odd numbered terms and the 30 term series of the even numbered terms. That is 2+6+4+12+6+24+... = 2+4+6+... +6+12+24+... The first series is arithmetic and the second one is geometric: to find the sum of 2+4+6+... to 30 terms we use the formula:, where , , and --- To find the sum of 6+12+24+... to 30 terms we use the formula: , where , , and ---------------- The sum of the two sequences is 930+6442450938 = 6442451868 Edwin