CREATE FUNCTION replace6plusint(@s1 varchar(100)) RETURNS TABLE AS RETURN
	WITH 
	firstRun AS (
		SELECT replace(replace(replace(replace(replace(replace(replace(replace(replace(replace(replace(@s1,'0','^'),'1','^'),'2','^'),'3','^'),'4','^'),'5','^'),'6','^'),'7','^'),'8','^'),'9','^'),'^^^^^^','------') a
		UNION ALL
		SELECT replace(a,'-^','--')
		FROM firstRun
		WHERE a like '%-^%'
	),
	secondRun AS (
		SELECT replace(a,'-','x') b, charindex('^', a) p
		FROM firstRun
		WHERE a not like '%-^%'
		UNION ALL
		SELECT stuff(b, p, 1, substring(@s1,p,1)), charindex('^', b)
		FROM secondRun
		WHERE p <> 0
	)
	SELECT b result FROM secondRun WHERE p = 0

SELECT name,
	REPLACE(
		REPLACE(
			REPLACE(
				REPLACE(
					REPLACE(name,
					'012345','xxxxxx'),
				'123456','xxxxxx'),
			'234567','xxxxxx'),
		'345678','xxxxxx'),
	'456789','xxxxxx') 
FROM t1

SELECT 
	t.name, x.New_Name 
FROM #t1 t
CROSS APPLY (
	SELECT New_Name = 
	(SELECT Newletter + ''
	FROM (	
		SELECT n, Newletter = CASE WHEN d.grouper IS NOT NULL 
				AND COUNT(*) OVER (PARTITION BY d.grouper) > 5 THEN 'x' ELSE letter END
		FROM (
			SELECT n, letter,
				grouper = ROW_NUMBER() OVER(PARTITION BY t.name ORDER BY ISNUMERIC(letter), n) - N 
			FROM (SELECT TOP(LEN(t.name)) n = ROW_NUMBER() OVER(ORDER BY (SELECT NULL)) 
					FROM sys.columns a, sys.columns b) tally
			CROSS APPLY (SELECT letter = SUBSTRING(t.name,n,1)) l
		) d
	) stri
	ORDER BY n
	FOR XML PATH('') , TYPE).value('.', 'varchar(max)')
) x
ORDER BY t.name

SELECT 
	t.name, x.New_Name 
FROM #t1 t
CROSS APPLY (
	SELECT New_Name = 
		(SELECT Newletter + ''
		FROM (	
			SELECT 
				n, Newletter = CASE WHEN ISNUMERIC(letter) = 1 -- d.grouper IS NOT NULL 
					AND COUNT(*) OVER (PARTITION BY d.grouper) > 5 THEN 'x' ELSE letter END
			FROM (
				SELECT t.name, n, letter,
					grouper = n - ROW_NUMBER() OVER(ORDER BY ISNUMERIC(letter) desc, n) 
				FROM 
				(SELECT TOP(LEN(t.name)) n = ROW_NUMBER() OVER(ORDER BY (SELECT NULL)) 
						FROM sys.columns a, sys.columns b) tally
				CROSS APPLY (SELECT letter = SUBSTRING(t.name,n,1)) l
			) d	
		) stri
		ORDER BY n
		FOR XML PATH('') , TYPE).value('.', 'varchar(max)')
) x
ORDER BY t.name