It was intended to be a "throwaway" song, the seldom-played B-side of a 45-rpm record produced in a New York recording studio in 1969.
Instead, it became an A-side No. 1 hit single for a band called Steam, a song whose simple but catchy chorus became an enduring sports anthem chanted by sports fans around the world to taunt an opposing team:
"Na Na Na Na. Na Na Na Na. Hey Hey Hey. Goodbye."
As a songwriter, producer and arranger, Leka was the co-writer and producer of the Lemon Pipers' 1968 No. 1 hit "Green Tambourine."
He also produced and arranged music for artists such as Harry Chapin ("Cat's in the Cradle"), the Peppermint Rainbow ("Will You Be Staying After Sunday"), Peter Nero, Paul Mauriat, the Left Banke and REO Speedwagon.
Then there was Steam and the song Leka referred to simply as "Na Na."
After spending two weeks at No. 1 on the Billboard chart in 1969, "Na Na Hey Hey Kiss Him Goodbye" took on a life of its own as the signature chant at sporting events across the country, including the Chicago White Sox, whose organist started playing the chorus in 1977.
It also caught on at soccer games overseas, where the "goodbye" in the chorus is substituted with "Adios!" in Spain, "Au Revoir!" in France, "Ciao! Ciao!" in Italy and "Sayonara!" in Japan.
The familiar chant also turned up in the 2000 movie "Remember the Titans" and in TV commercials.
"Na Na Hey Hey Kiss Him Goodbye" was written by Leka, Gary DeCarlo and Dale Frashuer, all of whom had been members of a band from Bridgeport, Conn., called the Chateaus in the early 1960s.
While working at Mercury Records in 1969, Leka persuaded the label to sign his friend DeCarlo, who was then singing solo under the name Garrett Scott.
After Leka recorded four singles with DeCarlo, a Mercury executive felt all four songs were A-side material.
With a new B-side needed quickly for DeCarlo's first single, they returned to the recording studio.
A studio visit by their friend Frashuer led them to resurrect a song they had written in 1961, "Kiss Him Goodbye."
"I thought it would be the perfect B-side, which used to be the throwaway songs you'd find on the back of every hit record," Leka said in a 2005 interview with the Arizona Republic. "But you had to make the B-sides long, and that way, the deejay is never going to play it."
As he told Fred Bronson in "The Billboard Book of Number 1 Hits": "I said we should put a chorus to it [to make it longer]. I started writing while I was sitting at the piano, going 'na na na na, na na na na … .' Everything was 'na na' when you didn't have a lyric." Someone else, Bronson wrote, added "hey hey hey."
They began recording the song in the early evening "without a full complement of musicians," Bronson wrote. Leka, who played keyboard, spliced in a drum track from one of DeCarlo's previously recorded songs.
When the Mercury executive heard "Na Na Hey Hey Kiss Him Goodbye," he said it sounded too good for a B-side and should be released as a separate single.
Leka told Bronson that it was an "embarrassing record" and an "insult," compared to DeCarlo's four other songs.
So he, DeCarlo and Frashuer agreed that "Na Na Hey Hey Kiss Him Goodbye" should be released by the Mercury subsidiary Fontana under the name of a fictitious band, one that became a one-hit wonder: Steam.
One of four children of Albanian immigrants, Leka was born in Bridgeport on Feb. 20, 1943. He began playing piano as a child and by the age of 16 was trying to sell his own songs to music publishers in New York.
In addition to his sister, Leka is survived by his wife, Engjellushe; their son, Alexander; two children from a previous marriage, Derek and Heather; and his brother, George.