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 A080208 #24 Feb 16 2025 08:32:48 %S A080208 1,1,1,1,1,8,95,31,85,59,1078,754,311,3508,1828,49957,22844 %N A080208 a(n) is the least k such that the generalized Fermat number (k+1)^(2^n) + k^(2^n) is prime. %C A080208 The first five terms correspond to the five known Fermat primes. The sequence A078902 lists some of the generalized Fermat primes. Bjorn and Riesel examined generalized Fermat numbers for k <= 11 and n <= 999. The sequence A080134 lists the conjectured number of primes for each k. %C A080208 For n >= 10, a(n) yields a probable prime. a(13) was found by _Henri Lifchitz_. It is known that a(14) > 1000. %H A080208 T. D. Noe, <a href="http://www.sspectra.com/math/GenFermatPrimes.txt">Table of generalized Fermat primes of the form (k+1)^2^m + k^2^m</a> %H A080208 Anders Björn and Hans Riesel, <a href="http://dx.doi.org/10.1090/S0025-5718-98-00891-6">Factors of generalized Fermat numbers</a>, Math. Comp. 67 (1998), no. 221, pp. 441-446. %H A080208 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/GeneralizedFermatNumber.html">Generalized Fermat Number</a> %F A080208 a(n) = A253633(n) - 1. %e A080208 a(5) = 8 because (k+1)^32 + k^32 is prime for k = 8 and composite for k < 8. %Y A080208 Cf. A019434, A078902, A080134, A153504, A152913, A194185, A253633. %K A080208 hard,more,nonn %O A080208 0,6 %A A080208 _T. D. Noe_, Feb 10 2003 %E A080208 a(14)-a(15) from _Jeppe Stig Nielsen_, Nov 27 2020 %E A080208 a(16) by _Kellen Shenton_ communicated by _Jeppe Stig Nielsen_, May 19 2023