**a(n) = sum{n/2<=k<=n, GCD(k,n)=1} k.**

*1, 1, 2, 3, 7, 5, 15, 12, 20, 16, 40, 18, 57, 33, 46, 48, 100, 41, 126, 60, 96, 85, 187, 72*

*2 seqfan posts*

Index of A-numbers in seqfan: by ascending order by month by frequency by keyword

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