Quote:
Originally Posted by 10metreh
2σ(a)a

Is there an OEIS entry for this sequence (starting with f(0)=3)?
Or, as a corollary, the secondary sequence g(n) where g(n) is the first index of f(n) which is divisible by the nth Mersenne prime?
Such that we know at least the first 873 terms of f(n); meanwhile g(1) = 0, g(2) = 2, g(3) = 29, with g(5) unknown as evidenced by this thread?
(Of course Mp  f(n) does not guarantee that the nth term loses the Mp driver, but it does mean that the sequence diverges from the f sequence.)