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 A275451 #15 Sep 16 2017 20:01:45
%S A275451 0,0,1,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,1,0,0,0,0,0,0,1,
%T A275451 1,2,2,1,1,0,2,1,1,1,1,1,0,0,0,1,1,1,3,0,0,3,2,2,1,1,1,1,2,0,5,4,4,2,
%U A275451 4,4,0,0,4,2,4,3,1,0,1,0,1,2
%N A275451 Number of occurrences of the string n in primorial(n).
%F A275451 a(A275450(n)) > 0.
%e A275451 Primorial(3) equals 30, which contains 3 once, therefore a(3) = 1.
%t A275451 primorial[n_]:=Product[Prime[i],{i,1,n}];
%t A275451 Table[Length[StringPosition[ToString[primorial[n]],ToString[n]]],{n,1,100}]
%t A275451 SequenceCount[IntegerDigits[#[[1]]],IntegerDigits[#[[2]]]]&/@With[ {nn=90}, Thread[ {FoldList[ Times,Prime[Range[nn]]],Range[nn]}]] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Sep 16 2017 *)
%Y A275451 Cf. A002110 (primorial numbers), A275450.
%K A275451 base,easy,nonn
%O A275451 1,36
%A A275451 _Ivan N. Ianakiev_, Jul 28 2016