**Let f(1,x)=x+1; f(n+1,x)=f(n,f(n,...f(n,x)...)), the formula contains x applications of f. This sequence is a(n)=f(n,2).**

*3, 4, 8, 204*

*5 seqfan posts*

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

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