The nth term of a sequence is a_n = (-1)^(n + 1)*(3n). What is the value of a_1 + a_2 + ... + a_{100}?
listfor(n, 1, 100, (-1)^(n+1)*(3*n)==
(3, -6, 9, -12, 15, -18, 21, -24, 27, -30, 33, -36, 39, -42, 45, -48, 51, -54, 57, -60, 63, -66, 69, -72, 75, -78, 81, -84, 87, -90, 93, -96, 99, -102, 105, -108, 111, -114, 117, -120, 123, -126, 129, -132, 135, -138, 141, -144, 147, -150, 153, -156, 159, -162, 165, -168, 171, -174, 177, -180, 183, -186, 189, -192, 195, -198, 201, -204, 207, -210, 213, -216, 219, -222, 225, -228, 231, -234, 237, -240, 243, -246, 249, -252, 255, -258, 261, -264, 267, -270, 273, -276, 279, -282, 285, -288, 291, -294, 297, -300)>>Total == - 150 sum of the sequence.
