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 A276741 #18 Dec 29 2016 19:31:18
%S A276741 0,1,7,31,37,71,235,515,1199,1815,6587,30429,35589,42147,58571
%N A276741 Integers n such that 10^n + 5^n + 2^n is a prime.
%C A276741 Corresponding primes of the form 10^n + 5^n + 2^n are {3, 17, 10078253, 10000000004656612873079540061773, 10000000000072759576141834396472156597, 100000000000000000000042351647362715016953416125036343281344004402684973, ...}
%C A276741 a(12) > 10000 if it exists. - _Felix Fröhlich_, Sep 17 2016
%C A276741 a(16) > 100000. - _Robert Price_, Dec 29 2016
%t A276741 Do[f=10^n+5^n+2^n; If[PrimeQ[f], Print[{n, f}]], {n, 1, 2000}]
%o A276741 (PARI) is(n) = ispseudoprime(10^n+5^n+2^n) \\ _Felix Fröhlich_, Sep 17 2016
%Y A276741 Cf. A125706.
%K A276741 hard,more,nonn
%O A276741 1,3
%A A276741 _René Gy_, Sep 16 2016
%E A276741 a(11) from _Felix Fröhlich_, Sep 17 2016
%E A276741 a(12)-a(15) from _Robert Price_, Dec 29 2016