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 A273937 #7 Jun 08 2016 01:51:11 %S A273937 49,90,206,314,375,578,949,2883,2959,3133,3409,6174,6185,16461,22313, %T A273937 24462,30249,45317,58169,60309,79202 %N A273937 Numbers n such that 7^n - 6^(n+1) is prime. %C A273937 a(22) > 10^5. - _Robert Price_, May 04 2016 %t A273937 Select[Range[12, 100000], PrimeQ[7^# - 6^(# + 1)] &] %o A273937 (PARI) is(n)=ispseudoprime(7^n-6^(n+1)) \\ _Charles R Greathouse IV_, Jun 08 2016 %Y A273937 Cf. A093765. %K A273937 nonn,more %O A273937 1,1 %A A273937 _Robert Price_, Jun 04 2016