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 A091409 #32 Aug 19 2025 09:42:15 %S A091409 1,3,9,220 %N A091409 a(n) is the smallest m such that A090822(m) = n. %H A091409 Dion C. Gijswijt, <a href="https://pyth.eu/uploads/user/ArchiefPDF/Pyth55-3.pdf">Krulgetallen</a>, Pythagoras, 55ste Jaargang, Nummer 3, Jan 2016. (Shows that the sequence is infinite) %H A091409 Fokko J. van de Bult, Dion C. Gijswijt, John P. Linderman, N. J. A. Sloane, and Allan R. Wilks, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL10/Sloane/sloane55.html">A Slow-Growing Sequence Defined by an Unusual Recurrence</a>, J. Integer Sequences, Vol. 10 (2007), #07.1.2. %H A091409 Fokko J. van de Bult, Dion C. Gijswijt, John P. Linderman, N. J. A. Sloane, and Allan R. Wilks, A Slow-Growing Sequence Defined by an Unusual Recurrence [<a href="http://neilsloane.com/doc/gijs.pdf">pdf</a>, <a href="http://neilsloane.com/doc/gijs.ps">ps</a>]. %H A091409 Levi van de Pol, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL28/Vandepol/vandepol5.html">The Growth Rate of Gijswijt's Sequence</a>, J. Int. Seq. (2025) Vol. 28, Art. No. 25.4.6. See p. 2. %H A091409 <a href="/index/Ge#Gijswijt">Index entries for sequences related to Gijswijt's sequence</a> %F A091409 a(n) is about 2^(2^(3^(4^(5^...^(n-1))))). %Y A091409 Cf. A090822. %K A091409 nonn %O A091409 1,2 %A A091409 _N. J. A. Sloane_, based on a suggestion from Dion Gijswijt (gijswijt(AT)science.uva.nl), Mar 04 2004 %E A091409 Sequence is infinite but next term, about 10^(10^23.09987) (see A091787), is too large to include.