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 Mar20 accepted What are the initial conditions for the Associated Stirling numbers of the second kind? Mar20 comment What are the initial conditions for the Associated Stirling numbers of the second kind? But then shouldn't S_2(2, 1) == 1 ? Mar20 comment What are the initial conditions for the Associated Stirling numbers of the second kind? What about for n or k < 0? The recurrence allows for this situation as N is reduced by R Mar20 asked What are the initial conditions for the Associated Stirling numbers of the second kind? Mar20 comment How many ways are there to divide elements into equal unlabelled sets? Thanks! Is there a way to generalize this such that: if I make D draws with replacement from N distinct items. how many ways are there to get C copies of any K distinct items. I tried to generalize with your analogy of "filling" in the bracket. But for D > C*K it's unclear how to no double count groups. Mar20 accepted How many ways are there to divide elements into equal unlabelled sets? Mar13 awarded Curious Mar12 awarded Commentator Mar12 comment How many ways are there to divide elements into equal unlabelled sets? Awesome :), is there a more compact formula that avoids the product? Mar12 comment How many ways are there to divide elements into equal unlabelled sets? Ah, so I should divide by the number of ways of ordering the sets = K! Mar12 comment How many ways are there to divide elements into equal unlabelled sets? Added. I'm concerned that I'm assuming some kind of ordering. @jameselmore Mar12 revised How many ways are there to divide elements into equal unlabelled sets? Added thoughts so far. Mar12 asked How many ways are there to divide elements into equal unlabelled sets? Feb26 accepted Code that minimizes the variance of sum of weighted random variables? Feb26 comment Code that minimizes the variance of sum of weighted random variables? I can't see to create a dataset for X and Y that give weights that aren't w1=0,w2=1 or w1=1,w2=0? Do you have a simple example? Feb26 comment Code that minimizes the variance of sum of weighted random variables? That's interesting thanks, given that we enforce (w1+w2=1) and w1,w2≥0 surely we would always use the sum of variables that gave weight 1 to the variable with smaller variance and 0 to the one with larger variance? Feb25 asked Code that minimizes the variance of sum of weighted random variables? Feb21 revised How do I count number of ways of drawing items with certain number of duplicates? added 207 characters in body Feb21 comment How do I count number of ways of drawing items with certain number of duplicates? @user314 I'll edit my post with an example. Feb21 asked How do I count number of ways of drawing items with certain number of duplicates?