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 A193570 #22 Feb 16 2025 08:33:15 %S A193570 77,98,145,149,194,238,283,289,298,328,358,382,385,419,456,465,491, %T A193570 538,546,564,583,645,654,678,687,707,768,770,786,789,798,809,823,829, %U A193570 832,835,853,867,876,879,890,892,897,908,914,928,941,978,980,982,987 %N A193570 Unhappy numbers which enter the cycle (4, 16, 37, 58, 89, 145, 42, 20) at 145. %H A193570 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/UnhappyNumber.html">Unhappy Number</a>. %e A193570 25889 is such a number of height 4 because it enters the cycle at 145 in 4 steps: 25889 -> 238 -> 77 -> 98 -> 145 -> 42 -> 20 -> 4 -> 16 -> 37 -> 58 -> 89 -> 145 -> ... %p A193570 S:=proc(n) local Q,k,N,z; Q:=[n]; for k from 1 do N:=convert(Q[k],base,10); z:=sum(N['i']^2,'i'=1..nops(N)); if not member(z,Q) then Q:=[op(Q),z]; else Q:=[op(Q),z]; break; fi; od; return Q; end: %p A193570 a:=[]: for i from 1 while nops(a)<30 do Q:=S(i); A:=Q[nops(Q)]; if A=145 then a:=[op(a),i] fi; od: print(op(a)); %Y A193570 Cf. A031177, A039943. %K A193570 nonn,base %O A193570 1,1 %A A193570 _Martin Renner_, Jul 31 2011