create or replace function pascal_triangle(n) as table (
  with recursive cte as (
    SELECT 0 as i, [1]::BIGINT[] as row,
    UNION ALL
    SELECT i+1 as i,
      ([1] || list_transform(row, (x,ix) -> x + (coalesce(row[ix+1], 0)))) as row
    FROM cte
    WHERE i < n
  )
  select row as "pascal_triangle" FROM cte
  order by i
);

.print The results for all n<=0 are the same:
select * as "pascal_triangle(0)" from pascal_triangle(0);
from pascal_triangle(4) _("pascal_triangle(4)");