0,3

a(5) = 4.602094... * 10^310, a(6) = 1.734184... * 10^(1.385368... * 10^310). - Amiram Eldar, Dec 12 2018

Francois Alcover, Table of n, a(n) for n = 0..5

a(0) = 0.

a(1) = 1.

a(2) = 2^(0+1) = 2.

a(3) = 2^(1+2) = 8.

a[0] = 0; a[1] = 1; a[n_] := a[n] = 2^(a[n-2] + a[n-1]); Array[a, 6, 0] (* Amiram Eldar, Dec 12 2018 *)

Cf. A000045.

Sequence in context: A282890 A004491 A132573 * A061591 A103085 A084148

Adjacent sequences: A322139 A322140 A322141 * A322143 A322144 A322145

nonn

Francois Alcover, Dec 11 2018

approved