fizzbuzz with SQL (imcomplete)

fizzbuzz.sql

CREATE OR REPLACE FUNCTION fizzbuzz(num Int) RETURNS SETOF Text AS $$
WITH RECURSIVE
fizz(f) AS (
    SELECT ARRAY[NULL,NULL,'fizz']
)
,buzz(b) AS (
    SELECT ARRAY[NULL,NULL,NULL,NULL,'buzz']
)
,fizzbuzz(fb) AS (
    SELECT
        concat(f,b)
    FROM(
        SELECT
            unnest(f) AS f,
            unnest(b) AS b
        FROM
            fizz, buzz
    )t
)
,r(rec, idx, fb) AS (
    SELECT
        1,
        row_number() OVER (),
        fb
    FROM
        fizzbuzz
    UNION ALL
    SELECT
        rec+1,
        15 * rec + row_number() OVER (),
        fb
    FROM
        r
    WHERE
        idx < num
)
SELECT
    fb
FROM
    r
WHERE
    idx <= num
$$ LANGUAGE SQL IMMUTABLE STRICT
;

SELECT fizzbuzz(100);