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## #1 2009-06-07 23:37:40

wintersolstice
Real Member
Registered: 2009-06-06
Posts: 125

### seven and thirteen

7 and 13 are the first two happy primes and 91 (7×13) is also a happy number. this means that 19 is happy, this is the 3rd happy prime!

Why did the chicken cross the Mobius Band?
To get to the other ...um...!!!

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## #2 2009-06-08 00:00:11

ganesh
Registered: 2005-06-28
Posts: 24,215

### Re: seven and thirteen

What are happy primes?

It is no good to try to stop knowledge from going forward. Ignorance is never better than knowledge - Enrico Fermi.

Nothing is better than reading and gaining more and more knowledge - Stephen William Hawking.

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## #3 2009-06-08 00:33:47

mathsyperson
Moderator
Registered: 2005-06-22
Posts: 4,900

### Re: seven and thirteen

Happy numbers are related to a sequence where each term is determined by the sum of the squares of the previous term's digits. eg.

7
49 (= 7²)
97 (= 4² + 9²)
130
10
1
1
1
...

A happy number is a number that initiates a sequence that goes to 1, like 7 does above.

An unhappy number will instead eventually fall into the following loop:
4, 16, 37, 58, 89, 145, 42, 20, 4...

Why did the vector cross the road?
It wanted to be normal.

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## #4 2009-06-09 18:36:13

DarkLightA
Member
Registered: 2009-05-27
Posts: 16

### Re: seven and thirteen

Hmm.. Never heard of this.. Is there a use for this sequence?

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## #5 2009-06-13 02:59:52

RickIsAnIdiot
Member
Registered: 2009-06-13
Posts: 5

### Re: seven and thirteen

Happy numbers are related to a sequence where each term is determined by the sum of the squares of the previous term's digits. eg.

7
49 (= 7²)
97 (= 4² + 9²)
130
10
1
1
1
...
For mathsyperson
Quote:

A happy number is a number that initiates a sequence that goes to 1, like 7 does above.

An unhappy number will instead eventually fall into the following loop:
4, 16, 37, 58, 89, 145, 42, 20, 4...

RickIsAnIdiot

Do you have any more Happy Number examples.

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## #6 2009-06-13 03:07:17

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

### Re: seven and thirteen

Hi Rick;

http://en.wikipedia.org/wiki/Happy_number

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #7 2009-06-14 00:37:05

RickIsAnIdiot
Member
Registered: 2009-06-13
Posts: 5

### Re: seven and thirteen

For bobbym
Quote:

http://en.wikipedia.org/wiki/Happy_number

RickIsAnIdiot

Thanks bobbym! keep up the good work..

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## #8 2009-06-14 01:23:58

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

### Re: seven and thirteen

Hi Rick;

Please don't be offended but I don't feel comfortable calling anyone an idiot so may I call you Rick. Anyway welcome to the forum.

Last edited by bobbym (2009-06-14 01:43:15)

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #9 2009-06-16 00:11:58

RickyIsAnIdiot
Banned
Registered: 2009-06-15
Posts: 18

### Re: seven and thirteen

For bobbym
Quote:
Hi Rick;

Please don't be offended but I don't feel comfortable calling anyone an idiot so may I call you Rick. Anyway welcome to the forum.

RickyIsAnIdiot

That's OK! you can call me Rick,#ick,#rick it's only names? Knowing the meaning's is the main thing...

Last edited by RickyIsAnIdiot (2009-06-16 00:13:47)

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## #10 2009-06-16 03:09:06

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

### Re: seven and thirteen

That's OK! you can call me Rick,#ick,#rick it's only names? Knowing the meaning's is the main thing...

I don't appreciate what you are trying to do here. The meaning... what are you implying?

Last edited by bobbym (2009-06-16 05:11:49)

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #11 2009-06-17 00:22:18

Kurre
Member
Registered: 2006-07-18
Posts: 280

### Re: seven and thirteen

There are two different accounts posting here, both RICKisanidiot and RICKYisanidiot, imo a clear violence to the multiple account rule (which I think exist on this forum?)

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## #12 2009-06-17 04:37:47

RickyIsAnIdiot
Banned
Registered: 2009-06-15
Posts: 18

### Re: seven and thirteen

Has Anyone Heard of "DRACULA" Numbers!

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