2 3 n 1 July 8, 2019 16 32 64 128 2 3 n 12 2 3 n 18 2 3 n 10 2 3 n 1 6 2 3 n 1 4 2 n 3 )+ 1 2n 5 1 2 3 n 1 formula 2 m 3 n 1 2 x 3 n 1 Sn 2 3 n 1 2 n 3 )= 4n 1 2 2n 3 1 n 1 2 3 n =- 1 12 1 2 3 n sum 1 2 3 n formula proof
