a(0)=1. For n >= 1, a(n) = the smallest prime either of the form a(n-1)*k - 1 or of the form a(n-1)*k + 1, for some k >= 2.

A162278

a(0)=1. For n >= 1, a(n) = the smallest prime either of the form a(n-1)*k - 1 or of the form a(n-1)*k + 1, for some k >= 2.