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## #1 2009-06-08 21:37:40

wintersolstice
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### 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...!!!

## #2 2009-06-08 22:00:11

ganesh
Moderator

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### Re: seven and thirteen

What are happy primes?

Character is who you are when no one is looking.

## #3 2009-06-08 22:33:47

mathsyperson
Moderator

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### 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.

## #4 2009-06-10 16:36:13

DarkLightA
Member

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### Re: seven and thirteen

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

## #5 2009-06-14 00:59:52

RickIsAnIdiot
Novice

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### 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.

## #6 2009-06-14 01:07:17

bobbym

Online

### 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.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

## #7 2009-06-14 22:37:05

RickIsAnIdiot
Novice

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### Re: seven and thirteen

For bobbym
Quote:

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

RickIsAnIdiot

Thanks bobbym! keep up the good work..

## #8 2009-06-14 23:23:58

bobbym

Online

### 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 23:43:15)

In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

## #9 2009-06-16 22:11:58

RickyIsAnIdiot
Banned

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### 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 22:13:47)

## #10 2009-06-17 01:09:06

bobbym

Online

### 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 (2009-06-17 03:11:49)

In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

## #11 2009-06-17 22:22:18

Kurre
Power Member

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### 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?)

## #12 2009-06-18 02:37:47

RickyIsAnIdiot
Banned

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### Re: seven and thirteen

Has Anyone Heard of "DRACULA" Numbers!