3 Jul
2013
3 Jul
'13
11:17 p.m.
Proof: f(x) := 1/sqrt(1-4*x) = sum_{n=0}^{\infty} \binom{2n}{n} x^n. Your sum is the coefficient of x^n in f(x)^2, i.e. the coefficient of x^n in 1/(1-4*x), which is 4^n. Victor On Wed, Jul 3, 2013 at 11:12 PM, Fred lunnon <fred.lunnon@gmail.com> wrote:
Prove sum_(j = 0)^(j = n) (2j)_C_j (2n-2j)_C_(n-j) = 4^n
eg. with n = 4 , 1.20 + 2.6 + 6.2 + 20.1 = 64
Fred Lunnon
_______________________________________________ math-fun mailing list math-fun@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/math-fun