Abstract :
The solution by Barbeau [Expressing one as a sum of distinct reciprocals: comments and a bibliography, Eureka (Ottawa) 3 (1977) 178–181] of the title equation where each image is a product of two distinct primes and image is improved to image, while the solution by Johnson [C. Rivera, J. Ayala, The prime puzzles & problems connection imageimage] requiring only that each image be of the form image with image distinct primes and image is improved to image. This improves also our earlier results with image [N. Burshtein, On distinct unit fractions whose sum equals 1, Discrete Math. 5 (1973) 201–206] and image [N. Burshtein, On distinct unit fractions whose sum equals 1, Discrete Math. 300 (2005) 213–217] in which only image for image is required.
