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PROJECT EULER · #0918

Recursive Sequence Summation

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The sequence an is defined by a1=1, and then recursively for n1: a2n=2ana2n+1=an3an+1 The first ten terms are 1,2,5,4,17,10,17,8,47,34.
Define S(N)=n=1Nan. You are given S(10)=13.
Find S(1012).

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