> > The length of the message (in bits) was a product of two primes. When the
> > sequence of bits was rasterred onto a rectangle whose sides were the
> > factors of the length of the message, a rather blocky bitmapped image
> >
> > "Aceribo message" would probably be a useful search term to find what was
> kind of insane aliens would think of that kind of thing?

Well, I don't think it's *that* obscure.  If you have the idea of it being
binary, the two-prime-number thing would suggest a rectangle to anyone who
has any half-decent maths, I'd think.  And (bigger if) if they have a sense
of bilateral symmetry they could even tell which reading is the right
one.  What I've always doubted is that they'd figure out anything much
encoded in the message.

Still, if they get that far it's enough to suggest there's some sort of
"intelligent life" out there, I'd have thought.

It's still a massive longshot, but I think the prime number thing is the
simplest bit of it. :)