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Both sides previous revision Previous revision Next revision | Previous revision Next revision Both sides next revision | ||
factorial_function [2015/11/14 03:07] nikolaj |
factorial_function [2015/11/14 03:26] nikolaj |
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0! = + 0^0 | 0! = + 0^0 | ||
1! = - 0^1 + 1*1^1, | 1! = - 0^1 + 1*1^1, | ||
- | 2! = + 0^2 - 2*1^2 + 2^2, | + | 2! = + 0^2 - 2*1^2 + 2^2, |
- | 3! = - 0^3 + 3*1^3 - 3*2^3 + 3^3, | + | 3! = - 0^3 + 3*1^3 - 3*2^3 + 3^3, |
- | 4! = + 0^4 - 4*1^4 + 6*2^4 - 4*3^4 + 4^4, | + | 4! = + 0^4 - 4*1^4 + 6*2^4 - 4*3^4 + 4^4, |
- | 5! = - 0^5 + 5*1^5 - 10*2^5 + 10*3^5 - 5*4^5 + 5^5, | + | 5! = - 0^5 + 5*1^5 - 10*2^5 + 10*3^5 - 5*4^5 + 5^5, |
- | 6! = + 0^6 - 6*1^6 + 15*2^6 - 20*3^6 + 15*4^6 - 6*5^6 + 6^6, | + | 6! = + 0^6 - 6*1^6 + 15*2^6 - 20*3^6 + 15*4^6 - 6*5^6 + 6^6, |
- | 7! = - 0^7 + 7*1^7 - 21*2^7 + 35*3^7 - 35*4^7 + 21*5^7 - 7*6^7 + 7^7, | + | 7! = - 0^7 + 7*1^7 - 21*2^7 + 35*3^7 - 35*4^7 + 21*5^7 - 7*6^7 + 7^7, |
8! = + 0^8 - 8*1^8 + 28*2^8 - 56*3^8 + 70*4^8 - 56*5^8 + 28*6^8 - 8*7^8 + 8^8 | 8! = + 0^8 - 8*1^8 + 28*2^8 - 56*3^8 + 70*4^8 - 56*5^8 + 28*6^8 - 8*7^8 + 8^8 | ||
</code> | </code> | ||
The binomial coefficients use the factorial of course, so there's not real computational benefit. | The binomial coefficients use the factorial of course, so there's not real computational benefit. | ||
+ | |||
+ | The theorem underlying here is that, for all $n$ | ||
+ | |||
+ | $\sum_{k=0}^n\dfrac{(-1)^k (-k)^n}{k!\,(n - k)!}=1$ | ||
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