This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A383236 #20 Apr 24 2025 13:34:55
%S A383236 1,2,3,4,4,5,5,6,6,7,7,8,5,6,7,8,8,9,9,10,9,10,10,11,10,11,11,12,6,7,
%T A383236 8,9,10,11,11,12,11,12,12,13,12,13,13,14,12,13,13,14,13,14,14,15,13,
%U A383236 14,14,15,14,15,15,16,7,8,9,10
%N A383236 The least number of applications of Ackermann-Péter functions to reach n, starting from 0.
%C A383236 The Ackermann-Péter function is A(k,m) = A143796(k,m).
%C A383236 n >= 1 is reached by finding some n = A(k,m) with k and m each either 0 or further nested application(s) of A.
%C A383236 This sequence is slow-growing.
%H A383236 Hendrik Ballhausen, <a href="/A383236/b383236.txt">Table of n, a(n) for n = 1..2048</a>
%H A383236 Rózsa Péter, <a href="https://xover.mud.at/~marty/iug2/rozsa_peter_1935b.pdf">Konstruktion nichtrekursiver Funktionen</a>, Mathematische Annalen, 111 (1935), 42-60.
%H A383236 Wikipedia, <a href="https://en.wikipedia.org/wiki/Ackermann_function">Ackermann function</a>
%F A383236 a(n) = min_{k,m: A(k,m)=n} a(k) + a(m) + 1
%e A383236 For n=65533, n = A(5,0) = A(A(2,1),0) = A(A(A(0,1),A(0,0)),0) = A(A(A(0,A(0,0)),A(0,0)),0) which is a(65533) = 5 applications of A, and this is the fewest possible.
%Y A383236 Cf. A143796 (Ackermann-Péter function).
%Y A383236 Cf. A368423 (with Wainer hierarchy).
%K A383236 nonn,look
%O A383236 1,2
%A A383236 _Hendrik Ballhausen_, Apr 20 2025