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 A275783 #7 Jun 13 2017 14:45:32 %S A275783 2,3,6,11,44,64,83,123,166,381,446,1221,1540,3156,5117,5476,6291,6353, %T A275783 13053,15158,23904,78288,82254,91230 %N A275783 Numbers n such that 10^n + 9^(n+1) is prime. %C A275783 a(25) > 10^5. %e A275783 3 is a member since 10^3 + 9^4 = 1000 + 6561 = 7561 which is a prime number. %t A275783 Select[Range[0, 100000], PrimeQ[10^# + 9^(# + 1)] &] %o A275783 (PARI) is(n)=ispseudoprime(10^n+9^(n+1)) \\ _Charles R Greathouse IV_, Jun 13 2017 %Y A275783 Cf. A093713, A082103, A093717, A093793, A096185, A093794, A093795, A096186, A271883, A271884. %K A275783 nonn,more %O A275783 1,1 %A A275783 _Robert Price_, Aug 08 2016