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.