no it will be (n* n+1) /2

when j=1 k runs 83

when j=2 k runs 82 times

similarly when j=83 k runs 0 times

so totally 83+82+81+...1+0 ==> (83*84)/2 => we can correlate this like 1+2+3+4 = 10 i.e. (4*5)/2

when j=1 k runs 83

when j=2 k runs 82 times

similarly when j=83 k runs 0 times

so totally 83+82+81+...1+0 ==> (83*84)/2 => we can correlate this like 1+2+3+4 = 10 i.e. (4*5)/2