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4.1.06

XXV

(the mandatory birthday post)

A quarter of a century, they say. Halfway to fifty, they say. This is not good enough. If you had said something like...
[25] is a square number, being 52 = 5 × 5, and it is also the sum of two squares, 32 + 42, often used in demonstrations of the Pythagorean theorem. It is the smallest square that is also a sum of two squares. 25 is a centered octagonal number and an automorphic number.

It is the first/smallest base 10 Friedman number as it can be expressed by its own numbers: 52.

It is also a Cullen number. 25 is the smallest pseudoprime satisfying the congruence 7n = 7 mod n. It is also a Somer pseudoprime based on 6.

Within base 10 one can readily test for divisibility by 25 by seeing if the last two digits of the number match 25, 50, 75 or 00. (Wikipedia)

Then I would have been impressed.

I just found out that this means that I am now eligble to run for President of the United States (if I was a citizen, that is). How about that?

4 Comments:

Anonymous the eye said...

Has it ever occurred to you that you and John McLaughlin have more than the guitar thing in common?

January 04, 2006 12:08 pm  
Blogger MGL said...

...No-oo...? I haven't. Though I do admit that our dazzling, unbridled virtuosity on the guitar do have more than a passing resemblance. What are you referring to?

January 04, 2006 12:43 pm  
Blogger MGL said...

You're kidding?? Wow. They both look really old for 25-year olds.

January 04, 2006 1:40 pm  
Anonymous the eye said...

the birthday, dude ... same as Dan Quayle's by the way

January 04, 2006 1:41 pm  

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