There is a syntax error
Sum[1/n,{n,1,10}]
All iterators in Mathematica (for functions as Table, Do, Sum) has the same form
{varname, upper value} - counts from 1 to uppr value
{varname, lower value, upper value) - counts from lower value to upper value in steps of 1
{varname, lower value, upper value, incerement} - the same as above but in steps of "incerement"
HTH
yehuda
