DAX formula

prashantg364 Here is one way, PBIX attached below signature. 

Measure 2 = 
    VAR __MinWeek = MINX( ALL('Table'[Week]), [Week] )
    VAR __MaxWeek = MAXX( ALL('Table'[Week]), [Week] )
    VAR __MaxWeekCell = MAX( 'Table'[Week] )
    VAR __Count = COUNTROWS( DISTINCT( 'Table'[Week] ) )
    VAR __Path = CONCATENATEX( DISTINCT( 'Table'[Week] ), [Week], "|", [Week], DESC )
    VAR __Table = 
        ADDCOLUMNS(
            GENERATESERIES( 1, __Count, 1 ),
            "__Week", PATHITEM( __Path, [Value] ) + 0
        )
    VAR __Table2 = 
        ADDCOLUMNS(
            __Table,
            "__Gap", 
                VAR __CurWeek = [__Week]
                VAR __Next = MAXX( FILTER( __Table, [__Week] < __CurWeek ), [__Week] )
                VAR __Result = IF( __CurWeek = __MaxWeekCell, 1, __CurWeek - __Next )
            RETURN
                __Result
        )
    VAR __GapWeek = MAXX( FILTER( __Table2, [__Gap] > 1 ), [__Week] )
    VAR __GapWeekFinal = 
        SWITCH( TRUE(),
            __MaxWeekCell <> __MaxWeek, BLANK(),
            __GapWeek = BLANK(), __MinWeek,
            __GapWeek
        )
    VAR __Result = IF( __GapWeekFinal = BLANK(), BLANK(), CONCATENATEX( FILTER( DISTINCT( 'Table'[Week] ), [Week] >= __GapWeek ), [Week], "/", [Week], DESC ) )
RETURN
    __Result