Project Euler task 53
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?
----------------------------------------------------
k = 0;
For[i = 1, i <= 100, i++,
For[j = 1, j < i, j++,
If[Binomial[i, j] > 1000000,
k++
]
]
]
k
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