Allen became Penn State's all-time leading rusher with 160 yards against Nebraska.
Andrew Rappleyea scored his first career touchdown against the Cornhuskers.
Littlejohn had 14 sacks in seven games as a junior.
With their college career ends in sight, Allen and Singleton are going out while etching their names in the Penn State history books.
Kaytron Allen broke Penn State's all-time rushing record with a 3-yard run in the top of the fourth quarter.
