A274992 a(n) = f_n(2), with f_0(x) = x+2, f_n+1(x) = (f_n)^x(x).

4, 6, 18, 6973568802

Offset

0,1

Comments

Next term is too large to include.

This function is a particular instance of the fast-iteration hierarchy function F[k]_n(x). Here we have f_n(x) = F[2]_n(x). See A275000 for details and definitions and formulae.

Links

Table of n, a(n) for n=0..3.

Mathematica

f[0, x_] := x + 2; f[n_, x_] := Nest[f[n - 1, # ]&, x, x]; Table[f[n, 2], {n, 0, 3}]

Crossrefs

Cf. A275000(F[n]_n(x)), A154714 (F[1]_n(x)).

Sequence in context: A005959 A057393 A196570 * A317584 A012928 A013160

Adjacent sequences: A274989 A274990 A274991 * A274993 A274994 A274995

Keyword

nonn

Author

Natan Arie Consigli, Oct 08 2016

Status

approved