[math-fun] Re: favorite theorem
28 Apr
2006
28 Apr
'06
9:10 p.m.
Let me say, only half in jest, that my favorite theorem in math is the classification theorem for finite sets, i.e., the fact that finite sets are classified up to isomorphism by the counting numbers (including zero)! Jim Propp
28 Apr
28 Apr
9:57 p.m.
My favorite "modest" theorem is: coefficient of x^n/n! in the series expansion of tan(x)+sec(x) is equal to the number of up-down permutations of [1,2,...,n]. Namely: tan(x)+sec(x)=1+(1)*x/1!+(1)*x^2/2!+(2)*x^3/3!+(5)*x^4/4!+... and 1; 12; 132, 231; 1324,1423,2314,2413,3412; Emeric Deutsch
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Emeric Deutsch -
James Propp