On the variation of certain fractional part sequences Michel Balazard; Leila Benferhat; Mihoub Bouderbala — 2021 Communications in Mathematics Let b > a > 0 . We prove the following asymptotic formula ∑ n ⩾ 0 | { x / ( n + a ) } - { x / ( n + b ) } | = 2 π ζ ( 3 / 2 ) c x + O ( c 2 / 9 x 4 / 9 ) , with c = b - a , uniformly for x ⩾ 40 c - 5 ( 1 + b ) 27 / 2 .