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CREATE SCHEMA IF NOT EXISTS pwc158;
CREATE OR REPLACE FUNCTION
pwc158.is_prime( v bigint )
RETURNS bool
AS $CODE$
DECLARE
i int;
BEGIN
FOR i IN 2 .. v - 1 LOOP
IF ( v % i = 0 ) THEN
RETURN false;
END IF;
END LOOP;
RETURN true;
END
$CODE$
LANGUAGE plpgsql;
CREATE OR REPLACE FUNCTION
pwc158.sum_digits( n bigint )
RETURNS int
AS $CODE$
WITH s(i) AS ( SELECT regexp_split_to_table( n::text, '' ) )
SELECT sum( i::bigint ) FROM s;
$CODE$
LANGUAGE SQL;
SELECT n
FROM generate_series( 1, 100 ) n
WHERE pwc158.is_prime( n )
AND pwc158.is_prime( pwc158.sum_digits( n ) );
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