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Arithmetic progression of second order

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April 26, 2010
number theory proposednumber theory

Problem Statement

Let (bn)n0=k=0n(a0+kd)(b_n)_{n \ge 0}=\sum_{k=0}^{n} (a_0+kd) for positive integers a0a_0 and dd. We consider all such sequences containing an element bib_i which equals 20102010. Determine the greatest possible value of ii and for this value the integers a0a_0 and dd.
(41th Austrian Mathematical Olympiad, regional competition, problem 4)