Forum User ID number.

[drew]

Originally Posted by Xyzzy

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

1873 is prime.

1873 = 28²+33²

You can arrange 12 3x3 LEGOs exactly 1873 different ways to build a contiguous structure that is symmetric when rotated by 90 degrees. (reference)

[Flatlander]

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 you think is cool about 1667?

[victor]

Originally Posted by Flatlander

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

Almost a beer brand. That's cool :D

cf http://www.k1664.co.uk/

[Richard Cameron]

Originally Posted by drew

You can arrange 12 3x3 LEGOs exactly 1873 different ways to build a contiguous structure that is symmetric when rotated by 90 degrees. (reference)

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.

[petrw1]

Originally Posted by victor

53.6563^2 = 2878.99852969 != 2879

I rounded a little

[masser]

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

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

[drew]

Originally Posted by Richard Cameron

I'm probably missing the point here, but i don't think lego do a 3x3 brick.

You're right, that's beside the point.

[m_f_h]

Originally Posted by Richard Cameron

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 ).

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.