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 A090263 #10 Dec 19 2019 11:20:56
%S A090263 1,37,41,53,59,79,83,119,133,151,179,197,223,241,263,283,299,349,361,
%T A090263 377,427,461,553,559,593,599,637,643,671,769,781,827,923,973,1103,
%U A090263 1117,1171,1327,1333,1361,1393,1399,1481,1493,1537,1549,1561,1619,1649,1823
%N A090263 Numbers n such that the strings n3n and 3n3 are both prime.
%H A090263 Daniel Starodubtsev, <a href="/A090263/b090263.txt">Table of n, a(n) for n = 1..10000</a>
%e A090263 37 is a member as 37337 and 3373 are both prime.
%t A090263 Select[Range[2000], PrimeQ[FromDigits @ Join[(d = IntegerDigits[#]), {3}, d]] && PrimeQ[FromDigits @ Join[{3}, d, {3}]] &] (* _Amiram Eldar_, Dec 07 2019 *)
%Y A090263 Cf. A090262, A090264, A090265.
%K A090263 base,nonn
%O A090263 1,2
%A A090263 _Amarnath Murthy_, Nov 28 2003
%E A090263 More terms from mohammed bouayoun (bouyao(AT)wanadoo.fr), Feb 02 2004