aqui esta la formula

Cybermatematico
Fri 12 Feb 12:49:53.981672 2010

aqui les va la formula para los que saben al menos restar y multiplicar y algo de ingles:

Choose the oldest age by which you want to get married, for example 39. Call this number 'n.’

Decide the earliest age at which you'll start to consider women as potential wives, for example, from 20 onwards. This number becomes 'p'.

Subtract 'p' from 'n' (20 from 39) then multiply the result by 0.368.

This gives you 6.992, which you should add to your minimum age (20).

The result of 27 (more or less) is your Optimal Proposal Age.

Read more: http://www.dailymail.co.uk/news/worldnews/article-1250250/Revealed-The-mathematical-formula-predicts-best-age-engaged.html#ixzz0fLg8leOy

Aqui les va la formula para los que saben matematicas:
∑ (n-k) (n-k-1) (n-k-2) … (n-k-r+2) x k x (1)
n (n-1) (n-2) (n-r+2) (n-r+1) (r-1)