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 A085412 #10 Apr 06 2017 11:20:43
%S A085412 6,8,11,12,22,27,29,36,37,42,44,67,68,71,72,73,74,75,76,133,134,138,
%T A085412 157,160,161,162,163,164,166,169,172,174,175,179,180,187,197,204,207,
%U A085412 210,232,235,237,247,249,251,254,261,263,264,269,272,278,282,285,287,303
%N A085412 Numbers n such that concatenation of prime[n] and first digit of prime[n] is prime.
%H A085412 Harvey P. Dale, <a href="/A085412/b085412.txt">Table of n, a(n) for n = 1..1000</a>
%e A085412 6 is a term because prime[6]=13 and concatenation of 13 and 1 is prime.
%t A085412 cpfdQ[n_]:=Module[{p=Prime[n]},PrimeQ[10p+IntegerDigits[p][[1]]]]; Select[ Range[ 400],cpfdQ] (* _Harvey P. Dale_, Apr 06 2017 *)
%Y A085412 Cf. A085413, A085414.
%K A085412 nonn,base
%O A085412 1,1
%A A085412 _Zak Seidov_, Jun 29 2003