e0015/euler0015.jl

@@ -0,0 +1,26 @@
+
+function euler0015(n::Integer)
+  n=big(n)
+  Int(div(prod(n+1:2n,1),factorial(big(n))))
+end
+
+function euler0015_2(n::Integer)
+  factorial(2*big(n))/factorial(big(n))^2
+end
+
+function euler0015_3(n::Integer)
+  n=big(n)
+  prod(n+1:2n,1)//factorial(big(n))
+end
+
+euler0015(3)
+@time result=euler0015(big(20))
+println(result)
+
+euler0015_2(3)
+@time result=euler0015_2(big(20))
+println(Int(result))
+
+euler0015_3(3)
+@time result=euler0015_3(big(20))
+println(result)