Does anyone know how to write the "Dell" symbol (the "upside-down" equilateral triangle that denotes the gradient)?

[ tex ] \nabla [ /tex ]

[tex]\nabla[/tex]

Hint: Search for "Gradient" in wikipedia :wink:

A couple cool tricks:

[tex]\today[2][/tex]


[tex]\calendar[/tex]

This one is just to see if the html linking works.


[html]
<img src=http://www.selectedplants.com/gardenphotos/sena.jpg>
[/html]

So it doesn't seem to pull this no matter how I modify the img string. Is it restricted to prevent attaching photos off of the net?

Fusion

Remote linking of images is dangerous because people can change the target down the road and inject in nasty pictures. It is much easier to just allow attachments.

(2^k)+1=prime????

k for 2=5

k for 4=17

k for 16=65537

k for 256=............

k for 65536=.............

k for 4294967296=...............

can it be?:help:

No.

2^256+1 has a factor 1238926361552897.

121645100409356287 is it a prime?

No:

121645 100409 356287 = 25561 x 4 759011 791767

Smaller numbers (<50 digits) can be easily tested with [url]http://www.alpertron.com.ar/ECM.HTM[/url]

thanks for your reply

Small ones can be checked in Linux.

[code]$ factor 121645100409356287
121645100409356287: 25561 4759011791767[/code]