Sum

Sum[f,{i,imax}] evaluates the sum ∑+i=1%imaxf. 

Sum[f,{i,imin,imax}] starts with i=imin. 

Sum[f,{i,imin,imax,di}] uses steps di. 

Sum[f,{i,{i1,i2,…}}] uses successive values i1, i2, ….

Sum[f,{i,imin,imax},{j,jmin,jmax},…] evaluates the multiple sum ∑+i=imin%imax∑+j=jmin%jmax…f. 

Sum[f,i] gives the indefinite sum ∑+if.

Please visit the official Wolfram Language Reference for more details and examples on core symbols.