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 A099647 #10 Jun 29 2025 01:56:47
%S A099647 35,36,46,53,57,63,64,75,135,138,153,156,165,183,237,245,246,254,264,
%T A099647 273,279,297,305,306,315,318,327,334,343,347,350,351,360,372,374,381,
%U A099647 388,406,425,426,433,437,452,460,462,473,503,507,513,516,524,530,531
%N A099647 Function f[n]=1+Sum[digit^2 of n] is iterated as in A099646. Values x for which A099646[x]=1 are listed here. These terms are analogous to happy-numbers [=A007770].
%C A099647 Iteration g[x] applied in A031176 is slightly modified to obtain actual function to iterate here: f[x]=1+g[x].Initial values resulting in fixed points are collected.
%e A099647 n=35 is here because list={36,46,53,[35],35,...} with transient t=3, c=1 cycle-length.
%t A099647 ed[x_] :=IntegerDigits[x]; f[x_] :=Apply[Plus, ed[x]^2]+1; itef[x_, ho_] :=NestList[f, x, ho]; tmc=Table[Length[Union[itef[w, 100]]], {w, 1, 256}]; c1=Table[Min[Flatten[Position[itef[w, Length[Union[itef[w, 100]]]] -Last[itef[w, Length[Union[itef[w, 100]]]]], 0]]], {w, 1, 256}]; Flatten[Position[tmc-(c1-1), 1]]
%Y A099647 Cf. A031176, A099645, A007770, A099646.
%K A099647 base,nonn
%O A099647 1,1
%A A099647 _Labos Elemer_, Nov 11 2004