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 A073237 #15 Jul 20 2024 19:49:24 %S A073237 1,4,37,1340164183006357436 %N A073237 a(n) = ceiling(Pi^Pi^...^Pi), where Pi appears n times. %C A073237 Decimal expansions (before taking ceiling) of Pi (A000796), Pi^Pi (A073233) and Pi^Pi^Pi (A073234) correspond to a(1), a(2) and a(3), respectively. See A073236 for same sequence rounded to nearest integer. This sequence is similar to A004002, which deals with e (but rounds). %C A073237 a(4) has 666262452970848504 digits. - _Martin Renner_, Aug 19 2023 %F A073237 a(n) = ceiling(Pi^Pi^...^Pi), where Pi occurs n times, a(0) = 1 (=Pi^0). %p A073237 p:= n-> `if`(n=0, 1, Pi^p(n-1)): %p A073237 a:= n-> ceil(p(n)): %p A073237 seq(a(n), n=0..3); # _Alois P. Heinz_, Jul 20 2024 %o A073237 (PARI) p=0; for(n=0,3, p=Pi^p; print1(ceil(p),",")) \\ n=4 produces too large an exponent for PARI. %Y A073237 Cf. A000796 (Pi), A073233 (Pi^Pi), A073234 (Pi^Pi^Pi), A073236 (Pi^Pi^...^Pi, n times, rounded), A004002 (Benford numbers), A056072 (similar to A004002 but takes floor). %K A073237 nonn %O A073237 0,2 %A A073237 _Rick L. Shepherd_, Jul 25 2002