Is there something like "combinatorics for dummies" on the web?
There are no smarties when it comes to Combinatorics, it is hard for everybody.
I think the best start is from the book Applied Combinatorics by Alan Tucker.
If you noticed each person solved the problem in a different way. I used a gf like EVW did. How gAr came up with his answer I do not know. I sometimes can not even describe my own methods to another person.
]]>Actually, the derivation ...
]]>How did gAr get that result?
Is there something like "combinatorics for dummies" on the web?
I did discover something exciting (to me, but seems trivial now). Distributing n snails among k people (where all the snails are the same):
Since we start with 1 for each person, it's n = 20 - 4 = 16
Any help on this notation gAr used would be appreciated.
]]>That is correct! Very good.
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The other case is when the n-1 snails are already grouped into k groups. There we just have to put the last snails into one of those groups, which we can also do in k ways, so the total number of ways for this case is k*a(n-1,k). Just add the two, and there you have it.
]]>]]>You look at what happens when you bring in another snail. You can either put it in a group with other snails or put it in a group of its own.