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 A361100 #28 Jan 31 2024 03:58:50 %S A361100 2,0,0,3,5,2,9,9,3,0,4,0,6,8,4,6,4,6,4,9,7,9,0,7,2,3,5,1,5,6,0,2,5,5, %T A361100 7,5,0,4,4,7,8,2,5,4,7,5,5,6,9,7,5,1,4,1,9,2,6,5,0,1,6,9,7,3,7,1,0,8, %U A361100 9,4,0,5,9,5,5,6,3,1,1,4,5,3,0,8,9,5,0 %N A361100 Decimal expansion of 2^(2^(2^(2^2))) = 2^^5. %C A361100 2^0 = 1, 2^1 = 2, 2^2 = 4, 2^2^2 = 2^^3 = (2^2)^2 = 16, %C A361100 2^2^2^2 = 2^^4 = (((2^2)^2)^2)^2 = 65536 %C A361100 so that 2^2^2^2^2 = 2^^5 = 2^(2^(2^(2^2))) = 2^65536 = 20035299304068464649790723515602557504478254755697514192650169737108940595563... %H A361100 Chai Wah Wu, <a href="/A361100/b361100.txt">Table of n, a(n) for n = 19730..39458</a> %H A361100 Googology Wiki, <a href="https://googology.fandom.com/wiki/Tetration">Tetration</a>. %H A361100 Pointless Large numbers stuff by Cookiefonster, <a href="https://sites.google.com/site/pointlesslargenumberstuff/home/2/uparrows">2.02 Knuth's Up-Arrows and the Hyper-Operators</a>. %H A361100 Robert P. Munafo, <a href="http://www.mrob.com/pub/math/seq-a094358.html">Sequence A094358, 2^^N = 1 mod N</a>. %F A361100 Equals 2^2^2^2^2 = 2^^5 = (((((((((((((((2^2)^2)^2)^2)^2)^2)^2)^2)^2)^2)^2)^2)^2)^2)^2)^2. %e A361100 2003529930406846464979072351560255750447825475569751419265016973710894059556311453089506130880933348 %e A361100 (...19529 digits omitted...) %e A361100 5775699146577530041384717124577965048175856395072895337539755822087777506072339445587895905719156736. %e A361100 The above example line shows the first one hundred decimal digits and the last one hundred digits with the number of unrepresented digits in parentheses. %t A361100 nbrdgt = 100; f[base_, exp_] := RealDigits[ 10^FractionalPart[ N[ exp*Log10[ base], nbrdgt + Floor[ Log10[ exp]] + 2]], 10, nbrdgt][[1]]; f[2, 2^2^2^2] %t A361100 IntegerDigits[2^65536][[;;100]] (* _Paolo Xausa_, Jan 31 2024 *) %o A361100 (Python) %o A361100 def A361100(n): return (1<<(1<<(1<<(1<<(1<<1)))))//10**(39458-n)%10 # _Chai Wah Wu_, Apr 03 2023 %Y A361100 Cf. A085667, A014221, A241291, A241292, A241293, A241294, A241295, A241296, A241297, A241298, A241299, A243913. %K A361100 nonn,cons,easy,fini,full %O A361100 19730,1 %A A361100 _Marco Ripà_, Mar 03 2023