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 A215487 #15 Jun 13 2025 02:02:56 %S A215487 3,7,19,79,431,1373,1801,2897,46997,341063,508867,720497,846913 %N A215487 Numbers k such that (7^k - 2^k)/5 is prime. %C A215487 All terms are prime. %C A215487 a(14) > 10^6. %H A215487 Jon Grantham and Andrew Granville, <a href="https://arxiv.org/abs/2307.07894">Fibonacci primes, primes of the form 2^n-k and beyond</a>, arXiv:2307.07894 [math.NT], 2023. %t A215487 Select[ Prime[ Range[1, 300] ], PrimeQ[ (7^# - 2^#)/5 ]& ] %o A215487 (PARI) is(n)=ispseudoprime((7^n-2^n)/5) \\ _Charles R Greathouse IV_, Jun 13 2017 %Y A215487 Cf. A004063, A028491, A057468, A059801, A121877, A128024, A128025, A128026, A128027, A128028, A128029, A128030, A128031, A128032. %K A215487 hard,more,nonn %O A215487 1,1 %A A215487 _Robert Price_, Aug 12 2012 %E A215487 a(10)-a(13) from _Jon Grantham_, Jul 29 2023