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## #1 2006-08-15 14:44:40

Nike
Member
Registered: 2006-08-15
Posts: 1

I want to know , what's the math name about such a special numbers:
A natural number, N, that can be written as the sum and product of a given set of at least two natural numbers, {a1, a2, ... , ak} is called a product-sum number: N = a1 + a2 + ... + ak = a1 a2 ... ak.

For example, 6 = 1 + 2 + 3 = 1 2 3.

is there any website solve this number like pi=3.1415.......and what 's its name? (like: An "NSW number"  (named after Newman, Shanks, and Williams) is an integer m that solves the Diophantine equation 2n^2==m^2+1)

any assistance will be appreciated!

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## #2 2006-08-23 21:40:55

krassi_holmz
Real Member
Registered: 2005-12-02
Posts: 1,905

which number I can't understand.
It seems interesting. Could you give more explanations?

IPBLE:  Increasing Performance By Lowering Expectations.

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## #3 2006-08-24 11:23:19

Zhylliolom
Real Member
Registered: 2005-09-05
Posts: 412

I believe you are talking about perfect numbers in the first part of your post(the part where you talked about 6).

I'm not sure exactly what to make of the rest of the post.

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## #4 2006-08-24 12:05:07

Ricky
Moderator
Registered: 2005-12-04
Posts: 3,791

I believe a special number is one that can be written as a sum of 2 or more consecutive numbers.

At least that's what my professor called it, but I can't seem to find it anywhere on the internet.

"In the real world, this would be a problem.  But in mathematics, we can just define a place where this problem doesn't exist.  So we'll go ahead and do that now..."

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## #5 2006-08-24 17:32:55

krassi_holmz
Real Member
Registered: 2005-12-02
Posts: 1,905

I tryed wiki and google but I couldn't find anything.

IPBLE:  Increasing Performance By Lowering Expectations.

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## #6 2006-08-24 21:04:57

ben
Member
Registered: 2006-07-12
Posts: 106

Try here for some fun along these lines

http://www.trottermath.net/numtrivia/specnum.html

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## #7 2006-08-29 22:14:05

krassi_holmz
Real Member
Registered: 2005-12-02
Posts: 1,905