Computation of π with PostgreSQL Recursive Query

pi.sql

-- just for fun
-- compute π using the Leibniz formula
with recursive leibniz (n, r) as (
  select 0, 0.
  union
  select n + 1, r + cast(power(-1, n) as decimal) / (2. * n + 1.)
  from leibniz
  where n < 10000
)
select 4. * r as pi from numbers offset 10000;