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 A333958 #28 Mar 29 2025 15:44:14 %S A333958 0,0,0,1,0,1,1,2,1,6,5,13,14,37,44,101,134,297,431,882,1361,2729,4405, %T A333958 8549,14311,27400,47101,89022,156080,293014,521730 %N A333958 The number of closed lambda calculus terms of size n that have a normal form, where size(lambda M)=2+size(M), size(M N)=2+size(M)+size(N), and size(V)=1+i for a variable V bound by the i-th enclosing lambda. %C A333958 This sequence is uncomputable, like the corresponding Busy Beaver sequence A333479, which takes the maximum normal form size of the a(n) terms that have one. %H A333958 Computed by changing "maximum $ (n,0,P Bot) :" in the main function of this <a href="https://github.com/tromp/AIT/blob/master/BB.lhs">Haskell program for analyzing Busy Beaver numbers</a> to "length". %e A333958 This sequence first differs from A114852 at n=18 where it excludes the shortest term without a normal form (lambda x. x x)(lambda x. x x), hence a(18) = 298-1 = 297. %Y A333958 Cf. A114852, A195691, A333479, A004147. %K A333958 nonn,more %O A333958 1,8 %A A333958 _John Tromp_, Apr 22 2020 %E A333958 Terms > 2729 corrected by _John Tromp_, Mar 29 2025