/* Try this */

data agename;
  input Name :$10.  age;
datalines;
Alfred 14
Alice 13
Barbara 13
Carol 14
Henry 14
James 12
Jane 12
Janet 15
Jeffrey 13
John 12
Joyce 11
Judy 14
Louise 12
Mary 15
Philip 16
Robert 12
Ronald 15
Thomas 11
William 15
;
run;

proc sort data=agename;
   by age;
run;

data agename_long;
    set agename;
        retain longname;
        by age;
        if first.age then longname = cats(age, ': ', name );
        else     longname = cats(longname, ',', ' ' , name);
        if last.age then output;
*        drop age name;
run;
proc sort data=agename_long; by descending age; run;

proc print data=agename_long; title 'AgeName-long'; run;