Hi I have a problem regarding summation and the index numbers. It is from a formula used in the betting industry.

"Consider a race withnrunners with starting prices (the odds of each horse) denoted bySi:1such that there areni(>0)horses atSi (i=1,2,3...,k)withS1<S2....Sk."

Letp= Σ ni/(1+Si)

I want to findpbut I don't understand the termsniandSi, help appreciated.

Regards,

Ian