might find this interesting...

IF OBJECT_ID('dbo.fn_TestCollatzConjecture') > 0

DROP FUNCTION dbo.fn_TestCollatzConjecture

GO

CREATE FUNCTION dbo.fn_TestCollatzConjecture ( @StartNumber BIGINT )

RETURNS VARCHAR(200)

AS

BEGIN

DECLARE @min-2 BIGINT

DECLARE @Levels INT

DECLARE @max-2 BIGINT

DECLARE @Ret VARCHAR(200) ;

WITH ApplyCollatzTransform

AS ( SELECT @StartNumber AS NewNumber ,

0 AS Level

UNION ALL

SELECT CASE WHEN NewNumber % 2 = 0

THEN NewNumber / 2

ELSE ( NewNumber * 3 ) + 1

END ,

Level + 1

FROM ApplyCollatzTransform ACT

WHERE NewNumber > 1

)

SELECT @min-2 = MIN(NewNumber) ,

@Levels = MAX(Level) ,

@max-2 = MAX(NewNumber)

FROM ApplyCollatzTransform

OPTION ( MAXRECURSION 0 )

IF @min-2 = 1

SET @Ret = 'Reached 1 after ' + CONVERT(VARCHAR(20), @Levels)

+ ' Level(s). Hit Max of ' + CONVERT(VARCHAR(20), @max-2)

+ ' before getting there...'

ELSE

SET @Ret = 'Did not hit 1 after ' + CONVERT(VARCHAR(20), @Levels)

+ ' Level(s)... Giving up...'

RETURN @Ret

END

go

DECLARE @StartNumber BIGINT

SET @StartNumber = 27

SELECT dbo.fn_TestCollatzConjecture(@StartNumber)