%I #8 Jun 07 2021 14:54:52
%S 0,1,2,4,256,3126,46662,823551,134217728,3486784402,100000000010,
%T 3138428376733,115909305827328,4240251492291543,166680102383370254,
%U 7006302246093750016
%N a(n) is obtained by replacing 2's by n's in the hereditary base-2 expansion of n.
%C The next term, a(16), has 22212093154093428530 digits, and is too large to include.
%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Goodstein's_theorem#Hereditary_base-n_notation">Hereditary base-n notation</a>
%F a(n) = A342707(n, n).
%e For n = 5:
%e - 5 = 2^2^2^0 + 2^0,
%e - so a(5) = 5^5^5^0 + 5^0 = 3126.
%Y Cf. A054382, A342707.
%K nonn
%O 0,3
%A _Rémy Sigrist_, Jun 04 2021