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 A303121 #15 Apr 23 2018 21:12:36 %S A303121 2,3,2,0,2,175,16,3,2,539,32,221,118,417,2,85,14,133,22,81,76,115,12, %T A303121 55,28,15,0,2465,110,31,232,117,230,3,12,851,4,375,2,1599,48,5461,46, %U A303121 15,218,6815,78,7,100,993,28,901,624,13,252,183,226,43247,104,5063,1348,777,1294,0,1806 %N A303121 Least k>1 such that k^n + n is prime, 0 if no such k exists. %C A303121 The values of n for which k^n + n is reducible over the integers are given in A097792. - _Joseph Myers_, _Allan C. Wechsler_ Apr 16 2018 %H A303121 Hugo Pfoertner, <a href="/A303121/b303121.txt">Table of n, a(n) for n = 1..365</a> %F A303121 If n + 1 is composite, then a(n) = A072883(n). - _Altug Alkan_, Apr 23 2018 %e A303121 a(2) = 3 because 3^2 + 3 = A303122(2) = 11 is prime, whereas 2^2 + 2 = 6 is composite. %Y A303121 Cf. A072883, A093324, A097764, A097792, A303122. %K A303121 nonn %O A303121 1,1 %A A303121 _Hugo Pfoertner_, Apr 23 2018