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 A215444 #30 Jun 01 2025 15:07:14 %S A215444 0,3,5,15,375,98003 %N A215444 Numbers k such that 7^k + k^7 + 1 is prime. %C A215444 a(6) > 8000. - _Joerg Arndt_, Sep 29 2012 %C A215444 a(7) > 2*10^5. - _Robert Price_, Jun 15 2014 %t A215444 Select[Range[0, 5000], PrimeQ[7^# + #^7 + 1] &] %o A215444 (Magma) [k: k in [0..400] | IsPrime(7^k + k^7 + 1)]; %o A215444 (PARI) is(n)=ispseudoprime(7^n+n^7+1) \\ _Charles R Greathouse IV_, Jun 06 2017 %Y A215444 Cf. A100357, A215441, A216423, A215442, A243934. %K A215444 nonn,hard,more %O A215444 1,2 %A A215444 _Vincenzo Librandi_, Sep 06 2012 %E A215444 a(6) from _Robert Price_, May 24 2014