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 A048129 #7 Jul 11 2014 16:20:04
%S A048129 393,422,614,674,692,886,889,934,993,1006,1270,1285,1502,1522,1524,
%T A048129 1542,1726,1822,2018,2217,2326,2386,2402,2474,2545,2654,2733,2734,
%U A048129 2761,2858,2876,3005,3022,3039,3054,3147,3193,3261,3453,3507,3512,3518,3589
%N A048129 Becomes prime or 4 after exactly 7 iterations of f(x) = sum of prime factors of x.
%C A048129 f(x) = sum of prime factors with multiplicity, so that f(1500) = 2+2+3+5+5+5 = 22.
%t A048129 spf[n_]:=Total[Flatten[Table[#[[1]],{#[[2]]}]&/@FactorInteger[n]]]; pf7Q[ n_]:= Module[ {lst=NestList[spf,n,7]},NoneTrue[Most[lst], PrimeQ] && !MemberQ[Most[lst],4]&&(PrimeQ[Last[lst]]||Last[lst]==4)]; Select[Range[ 3600],pf7Q] (* _Harvey P. Dale_, Jul 11 2014 *)
%K A048129 nonn
%O A048129 1,1
%A A048129 _David W. Wilson_