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 A330699 #10 Dec 29 2019 13:10:46 %S A330699 7,11,13,37,41,47,59,61,71,79,83,101,103,149,181,191,193,229,241,307, %T A330699 317,347,359,373,383,409,439,467,487,509,569,691,823,839,857,907,941, %U A330699 1061,1069,1091,1109,1123,1181,1193,1303,1423,1447,1487,1499,1579,1601,1697,1777,1831,1871,1931,1949,1979 %N A330699 Primes p such that the base-10 concatenation p||(p+1)||p is prime. %H A330699 Robert Israel, <a href="/A330699/b330699.txt">Table of n, a(n) for n = 1..10000</a> %e A330699 a(3)=13 is a member because 13 and 131413 are primes. %p A330699 f:= proc(n) local d; d:=10^(ilog10(n)+1); %p A330699 n*(d^2+d+1)+d %p A330699 end proc: %p A330699 select(t -> isprime(t) and isprime(f(t)), [seq(i,i=3..10000,2)]); %Y A330699 Cf. A261618, A309935. %K A330699 nonn,base %O A330699 1,1 %A A330699 _Robert Israel_, Dec 26 2019