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 A193996 #7 Mar 30 2012 17:23:02 %S A193996 4,16,20,37,42,58,89,145,78999,79899,79989,79998,87999,89799,89979, %T A193996 89997,97899,97989,97998,98799,98979,98997,99789,99798,99879,99897, %U A193996 99978,99987,378999,379899,379989,379998,387999,389799,389979,389997,389999,397899,397989 %N A193996 Numbers that require exactly 8 iterations to determine that they are happy or not (A007770 and A031177). %C A193996 This sequence begins with the last 8 numbers of A039943. The number 78999 is the first happy number here. %t A193996 f[n_] := Total[IntegerDigits[n]^2]; Select[Range[400000], Length[NestWhileList[f, #, UnsameQ, All]] - 1 == 8 &] %K A193996 nonn,base %O A193996 1,1 %A A193996 _T. D. Noe_, Aug 23 2011