Thread: Proving Cardinality

Hello,
Urgently need some help with some Mathematical Communication.
The question is:
Show that the set of all odd square numbers {1,9,25,49,...} has cardinality ℵ0 [aleph-zero].

Any ideas?

Originally Posted by Ellis

Show that the set of all odd square numbers {1,9,25,49,...} has cardinality ℵ0 [aleph-zero].

The -th non-negative odd number is ...

Can you use this to find a bijection which maps onto ?

What is the largest cardinality, because surely I can start with the cardinality of the set of all Real numbers and then work from there?

Originally Posted by Ellis

What is the largest cardinality

I don't know.

because surely I can start with the cardinality of the set of all Real numbers and then work from there?

I don't think so.