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 A265485 #19 Aug 22 2025 17:39:42 %S A265485 1,2,12,14,110,2574,10964,24257,44364 %N A265485 Numbers k such that 49^k - 7^k - 1 is prime. %C A265485 For k = 1, 2, 12, 14 the corresponding primes are 41, 2351, 191581231366725127199, 459986536544061737903951. %C A265485 a(10) > 10^5. - _Robert Price_, Dec 25 2019 %e A265485 2 is in the sequence because 49^2 - 7^2 - 1 = 2351 is prime. %t A265485 Select[Range[2000], PrimeQ[49^# - 7^# - 1] &] %o A265485 (Magma) [n: n in [0..1000] | IsPrime(49^n - 7^n - 1)]; %o A265485 (PARI) for(n=1, 1e3, if(ispseudoprime(49^n - 7^n - 1), print1(n, ", "))) \\ _Altug Alkan_, Dec 12 2015 %Y A265485 Cf. similar sequences listed in A265481. %K A265485 nonn,more %O A265485 1,2 %A A265485 _Vincenzo Librandi_, Dec 12 2015 %E A265485 a(6) from _Ray Chandler_, Sep 25 2019 %E A265485 a(7)-a(9) from _Robert Price_, Dec 25 2019