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 A073236 #25 Jul 20 2024 19:48:05 %S A073236 1,3,36,1340164183006357435 %N A073236 Pi^Pi^...^Pi (n times) rounded to nearest integer. %C A073236 Decimal expansions (before rounding) of Pi (A000796), Pi^Pi (A073233) and Pi^Pi^Pi (A073234) correspond to a(1), a(2) and a(3), respectively. All four terms are equivalent if floor is used instead of round. See A073237 for same sequence but using ceiling. This sequence is the analog of A004002, which deals with e. %C A073236 a(4) has 666262452970848504 digits. - _Mateusz Winiarski_, Mar 23 2020; corrected by _Martin Renner_, Aug 23 2023 %F A073236 a(n) = round(Pi^Pi^...^Pi), where Pi occurs n times, a(0) = 1 (=Pi^0). %p A073236 p:= n-> `if`(n=0, 1, Pi^p(n-1)): %p A073236 a:= n-> round(p(n)): %p A073236 seq(a(n), n=0..3); # _Alois P. Heinz_, Jul 20 2024 %t A073236 Round[NestList[Power[Pi, #] &, 1, 3]] (* _Alonso del Arte_, Jul 02 2014 *) %o A073236 (PARI) p=0; for(n=0,3, p=Pi^p; print1(round(p),",")) \\ n = 4 produces too large an exponent for PARI. %Y A073236 Cf. A000796 (Pi), A073233 (Pi^Pi), A073234 (Pi^Pi^Pi), A073237 (Ceiling of Pi^Pi^...^Pi, n times), A004002 (Benford numbers). %K A073236 nonn %O A073236 0,2 %A A073236 _Rick L. Shepherd_, Jul 25 2002