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 A094406 #14 Aug 31 2025 09:30:00 %S A094406 4,2,11,15,5,3,14,45,36,6,112,269,15999 %N A094406 Smallest unhappy number that takes n steps to reach any of the unhappy cycle (4, 16, 37, 58, 89, 145, 42, 20) under iteration of sum of squares of digits map. %C A094406 This sequence is an analog of sequence A001273 with the unhappy numbers instead of the happy numbers. %C A094406 The next term, 577999999999....999999999999 (199 digits) is too large to include. %H A094406 Michel Marcus, <a href="/A094406/b094406.txt">Table of n, a(n) for n = 4..17</a> %H A094406 Walter Schneider, <a href="http://web.archive.org/web/2004/www.wschnei.de/digit-related-numbers/happy-numbers.html">Unhappy Numbers</a>. %e A094406 15 is the fourth term because: 15: 1^2 + 5^2 = 26 / 26: 2^2 + 6^2 = 40 / 40: 4^2 + 0^2 = 16 and 16 is a member of the unhappy number series (4, 16, 37, 58, 89, 145, 42, 20) %Y A094406 Cf. A001273. %K A094406 nonn,base,changed %O A094406 4,1 %A A094406 _Sergio Pimentel_, Apr 30 2004 %E A094406 Edited by _Charles R Greathouse IV_, Aug 03 2010