1/(2+4)+1/(2+4+6)+1/(2+4+6+8)+...+1/(2+4+6+8+...+50)=1/(2^2+2)+1/(3^2+3)+…1/(n^2+n)+…1/(25^2+25)=1/[2(2+1)]+1/[3(3+1)]+…1/[n(n+1)]+…1/[25(25+1)]=(1/2-1/3)+(1/3-1/4)+…[1/n-1/(n+1)]+…(1/25-1/26)=1...