How can I generate a series of repeating numbers in PostgreSQL?

Question

In PostgreSQL, is it possible to generate a series of repeating numbers? For example, I want to generate the numbers 1 to 10, with each number repeated 3 times:

Answer 1

For such small numbers CROSS JOIN two VALUES expressions:

SELECT n
FROM  (VALUES (1),(2),(3)) x(r)  -- repetitions (values are not used)
     ,(VALUES (1),(2),(3),(4),(5),(6),(7),(8),(9),(10)) y(n); -- numbers

SQL Fiddle.

This works for any sequence of numbers (including repeated or irregular patterns).
For anything bigger and with regular sequential pattern use generate_series() as has been suggested.