B=1pe1+ 1pe2+1pe3+1pe4+...+1pe2017+1pe2+2pe3+3pe4+...+2016pe2017=
=1/1 +1/2 +1/3 +1/4 +...+1/2017+
+1/2 +2/3 +3/4 +...+2016/2017=
=1+(1/2 +1/2)+(1/3 +2/3)+(1/4 +3/4)+...+(1/2017 +2016/2017)=
=1+(1+1)/2 +(1+2)/3 +(1+3)/4 +...+(1+2016)/2017=
1+1+1+1+...+1 (de 2017 ori)=2017