[bgill]

Although Obama transferred to Columbia University in 1981 at the end of his sophomore year, the significance of the two years he spent at Occidental was a theme that ran through much of the reporting about his candidacy... It was at Occidental where he stopped being called “Barry” and became Barack Obama

Per your oxy.ed link. He was there in '79-'81. The '80 divorce and name change fits.

[etraveler13]

Your quite right.
Born 1961
Soetoro Divorce 1980 - 19 years old
Occidental College 1979-1981 - 20 years old
Columbia College (transfer in 1981) - 21 years old
Name changed in 1981 (illegally) at 21 years old.
He kept the name Barry Soetoro and his passport to his 21st birthday. And Indonesian law allows foreign travel for education to continue citizenship past the 5 year mark.
Coincidentally, Obama travelled back to Indonesia to visit his Mother and Sister, which reaffirmed his citizenship, prior to his visit to Pakistan with a valid passport (Presumably Indonesian)
IMO...it fits.