Forum User ID number.
 

Post something (mathematically) interesting about your forum User ID number.

(14^n - 1)/13 is prime with n=my forum-ID and much more: [URL="http://www.research.att.com/~njas/sequences/?q=2687&sort=0&fmt=0&language=english&go=Search"]http://www.research.att.com/~njas/sequences/?q=2687&sort=0&fmt=0&language=english&go=Search[/URL]

518 is an untouchable number.
518!!+1 is prime.
phi(518) is a perfect cube.
518^3-1/517 is prime.

The number after 517 and before 519. (Interesting for those who do not know how to count):grin:

(More facts available on request)
:popcorn:

2656 is the sum of the totient function for the first 93 integers.
2656*30+11, +13, +17, and +19 are prime quadruplets.

2044 = 2^11-4
:)

2879 is a PRIME!!

2*8 = 7+9

The square root of 2879 is 53.6563.
536563 is also a prime

[QUOTE=petrw1;104236]The square root of 2879 is 53.6563.
536563 is also a prime[/QUOTE]

53.6563^2 = 2878.99852969 != 2879 :no:

2044^2/(596848) is prime :whistle:

(538^5-1)/(538-1) is prime

Let's see... i'll do my post count:

532 is 9 digits away from both it's neighboring primes: 523 and 541.

532 - 523 = 9
532 - 541 = -9

and if one shifts the last two didgits of the ID number up/down and down/up (1/-1 and -1/1) it yeilds the neighboring primes.

532
+1/-1
------
541

532
-1/+1
------
523

This relation probably has a name; i don't know it.

2716^1856+1 Prime [6374 digits]
15*2716^15+1 prime [cullen; 53 digits]
278*2716^278-1 prime [woodall; 958 digits]

[QUOTE=roger;104320]2716^1856+1 Prime [6374 digits]
[/QUOTE]

This is not prime.

[QUOTE=Xyzzy;104164]Post something (mathematically) interesting about your forum User ID number.[/QUOTE]

1873 is prime.

1873 = 28[sup]2[/sup]+33[sup]2[/sup]

You can arrange 12 3x3 LEGOs exactly 1873 different ways to build a contiguous structure that is symmetric when rotated by 90 degrees. ([url=http://www.research.att.com/~njas/sequences/A123834]reference[/url])

1667 is prime.
667 is prime.
67 is prime.
7 is prime.
(OK, I lied about one of them!)

It appears in lots of integer sequences, but what do [I]you [/I]think is cool about 1667?

[QUOTE=Flatlander;104350]It appears in lots of integer sequences, but what do [I]you [/I]think is cool about 1667?[/QUOTE]
Almost a beer brand. That's cool :D

cf [url]http://www.k1664.co.uk/[/url]
:victor:

[QUOTE=drew;104345]You can arrange 12 3x3 LEGOs exactly 1873 different ways to build a contiguous structure that is symmetric when rotated by 90 degrees. ([url=http://www.research.att.com/~njas/sequences/A123834]reference[/url])[/QUOTE]
I'm probably missing the point here, but i don't think lego do a 3x3 brick. ( I could be wrong; I've just read that they do do a 1x14 that i've never seen )

There weren't any pictures at the end of that link, unfortunately.

[QUOTE=victor;104268]53.6563^2 = 2878.99852969 != 2879 :no:
[/QUOTE]


I rounded a little :blush:

5!+6!+1! = 29^2

Much more interesting, however, is that 561 is the smallest Carmichael number.

[QUOTE=Richard Cameron;104357]I'm probably missing the point here, but i don't think lego do a 3x3 brick.[/QUOTE]
You're right, that's beside the point.

[quote=Richard Cameron;104357]I'm probably missing the point here, but i don't think lego do a 3x3 brick. ( I could be wrong; I've just read that they do do a 1x14 that i've never seen ).[/quote]
IIRC, the standard height is 3 times the height of the flat bricks, so a 1x3 brick of standard height can be decomposed in 3x3 "elementary" (flat) 1x1 bricks.