MathDB
a_1 = 1, a_{n + 1} = [\sqrt{a_1+a_2+...+a_n} ]

Source: Germany Federal - Bundeswettbewerb Mathematik 2010, round 2, p2

April 14, 2020
floor functionrecurrence relationSequenceradicalalgebra

Problem Statement

The sequence of numbers a1,a2,a3,...a_1, a_2, a_3, ... is defined recursively by a1=1,an+1=⌊a1+a2+...+an⌋a_1 = 1, a_{n + 1} = \lfloor \sqrt{a_1+a_2+...+a_n} \rfloor for n≥1n \ge 1. Find all numbers that appear more than twice at this sequence.
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