## Combinatoric selections

### Problem 53

Published on Friday, 26th September 2003, 06:00 pm; Solved by 28891

There are exactly ten ways of selecting three from five, 12345:

123, 124, 125, 134, 135, 145, 234, 235, 245, and 345

In combinatorics, we use the notation, 5C3 = 10.

In general,

nCr = | n! r!(nr)! | ,where r n, n! = n(n1)...321, and 0! = 1.

It is not until n = 23, that a value exceeds one-million: 23C10 = 1144066.

How many, not necessarily distinct, values of nCr, for 1 n 100, are greater than one-million?