Question Number 104296 by Dwaipayan Shikari last updated on 20/Jul/20

    FUN TIME AGAIN!          S_n =1+2+3+4+5+6+7+8+9+..  S_n =1+(2+3+4)+(5+6+7)+...  S_n =1+9+18+27+...  S_n =1+9(1+2+3+4+5+6+7.......)  S_n =1+9S_n   S_n =−(1/8)         S_n =1−1+1−1+1−1+1−1+1−1+..  S=(1/2)       S_n =1−2+4−8+16−32+.....  S_n =(1/(1+2))=(1/3)      S_n =1+2+4+8+16+...  S_n =1+2(1+2+4+8+...)  S_n =1+2(1+2(1+2+4+8+...)  S_n =1+2(1+2S_n )  −3S_n =3⇒S_n =−1