**phi(n), where phi(n) is multiplicative with phi(2) = 1; phi(4) = 2; phi(2^a) = 2^(a-2)+2 if a>2; phi(p^a) = (p-1)*p^(a-1)/2 if prime p>2 and a>0.**

*1, 1, 2, 2, 3, 2, 4, 4, 4, 3, 6, 4, 7, 4, 6, 6, 9, 4, 10, 6, 8, 6, 12, 8, 11, 7, 10, 8, 15, 6, 16*

*3 seqfan posts*

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

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