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 A245315 #16 Jul 03 2019 15:34:05
%S A245315 422,623,8222,933,1025,12223,1427,1535,162222,18233,20225,2137,22211,
%T A245315 242223,2555,26213,27333,28227,30235,3222222,33311,34217,3557,362233,
%U A245315 38219,39313,402225,42237,442211,45335,46223,4822223
%N A245315 Concatenate n-th composite number with concatenation of its prime factors in ascending order.
%H A245315 Jens Kruse Andersen, <a href="/A245315/b245315.txt">Table of n, a(n) for n = 1..10000</a>
%e A245315 a(1)=422 since 4=2*2 and 4 is the first composite integer.
%t A245315 f[n_]:=FactorInteger[n];con[A_]:=(v1={};l=Length[A];Do[v1=Join[v1,IntegerDigits[A[[k]]]],{k,l}];FromDigits[v1]);alfa[n_]:=(b=f[n];j=Length[b];c=Table[Table[b[[k]][[1]],{b[[k]][[2]]}],{k,j}];w={};Do[w=Join[w,c[[k]]],{k,j}];con[w]);na[n_]:=con[{n,alfa[n]}];v=Select[Range[2,1000],!PrimeQ[#]&];Table[na[v[[k]]],{k,32}]
%t A245315 ncpf[n_]:=FromDigits[Join[IntegerDigits[n],Flatten[IntegerDigits/@Table[ #[[1]], #[[2]]]&/@FactorInteger[n]]]]; ncpf/@Select[Range[ 100], CompositeQ] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Jul 03 2019 *)
%Y A245315 Cf. A002808, A245316.
%K A245315 nonn,base
%O A245315 1,1
%A A245315 _Jahangeer Kholdi_, Sep 15 2014