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 A236551 #12 Jan 29 2014 13:22:47
%S A236551 2,13,311,313,419,641,643,647,653,761,983,997,9103,11131,11149,12157,
%T A236551 12163,14197,15227,15233,18307,18311,18313,20353,20359,21379,21383,
%U A236551 21397,22409,23431,24499,25523,25541,26557,29599,30631,30643,30661,30677,31727,33773
%N A236551 Primes formed from concatenation of PrimePi(n) and prime(n).
%H A236551 K. D. Bajpai, <a href="/A236551/b236551.txt">Table of n, a(n) for n = 1..1461</a>
%e A236551 pi(6) = 3: prime(6) = 13. Concatenation of 3 and 13 gives 313 which is prime and appears in the sequence.
%e A236551 pi(8) = 4: prime(6) = 19. Concatenation of 4 and 19 gives 419 which is prime and appears in the sequence.
%p A236551 with(StringTools): with(numtheory): KD := proc() local a,b,d; a:=pi(n); b:=ithprime(n); d:=parse(cat(a,b)); if isprime (d) then RETURN (d); fi; end: seq(KD(), n=1..300);
%t A236551 Select[Table[FromDigits[Flatten[{IntegerDigits[PrimePi[n]], IntegerDigits[Prime[n]]}]], {n, 100}], PrimeQ] (* _Alonso del Arte_, Jan 28 2014 *)
%Y A236551 Cf. A030458 (primes: concatenation of n and n+1), A084667 (primes: concatenation of n and prime(n)), A084669 (primes: concatenation of prime(n) and n).
%K A236551 nonn,base,less
%O A236551 1,1
%A A236551 _K. D. Bajpai_, Jan 28 2014