PARIS, Aug. 26 — Raymond Barre, a prominent economist who was prime minister of France from 1976 to 1981, died in Paris on Saturday. He was 83. Mr. Barre died in the Val-de-Grâce military hospital, where he had been since April after a heart attack, his family said. Mr. Barre, a centrist, was a longstanding figure in French political life. Considered by some to be the foremost French economist of the second half of the 20th century, he brought a scholarly distance to his political involvement.