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•  » GCD(sum_(i=1 to N) i!, sum_(i=1 to N+1) i!) = 99 for N >= 10

## #1 2012-12-29 00:07:17

pellerinb
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### GCD(sum_(i=1 to N) i!, sum_(i=1 to N+1) i!) = 99 for N >= 10

Just curious if anyone else has observed this. I have found it true up to N = 1 million.

GCD(sum_(i=1 to N) i!, sum_(i=1 to N+1)  i!) = 99 for N >= 10

I'm thinking it might be easy to prove this too... I'm not sure though.

Prime numbers have got to be the neatest things; they are like atoms. Composites are two or more primes held together by multiplication.
In biology, we use math like we know what we are talking about. Sad isn't it.

## #2 2012-12-31 23:32:49

Agnishom
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### Re: GCD(sum_(i=1 to N) i!, sum_(i=1 to N+1) i!) = 99 for N >= 10

The question seems interesting, could you please make it clear with latex?

'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
'The whole person changes, why can't a habit?' -Alokananda

## #3 2012-12-31 23:55:56

pellerinb
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### Re: GCD(sum_(i=1 to N) i!, sum_(i=1 to N+1) i!) = 99 for N >= 10

I don't know how to input latex into this forum but I can tell you that if you enter 'sum_(i=1)^10 i! ; sum_(i=1)^11 i!' without quotes into the Wolfram|Alpha website or iPhone/iPad app, you will see the desired equations and their GCD.

Prime numbers have got to be the neatest things; they are like atoms. Composites are two or more primes held together by multiplication.
In biology, we use math like we know what we are talking about. Sad isn't it.

## #4 2013-01-01 01:44:33

muxdemux
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### Re: GCD(sum_(i=1 to N) i!, sum_(i=1 to N+1) i!) = 99 for N >= 10

Latex here:

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