Neil Sedaka, the million-selling singer and songwriter, has died. His many hits included “Breaking Up Is Hard to Do,” “Calendar Girl” and “Oh! Carol,” a lament for his high school sweetheart, Carole King. Among those covering his work were Elvis Presley, Frank Sinatra and the Captain & Tennille, whose version of “Love Will Keep Us Together” was a No. 1 smash in 1975. Sedaka kept performing dozens of concerts a year well into his 80s. He retained the enthusiasm and broad vocal range of his youth and never tired of the standards he had sung hundreds of times.