%I #13 Jan 08 2024 16:47:36

%S 2,5,17,5,257,5,17,5,65537,5,17,5,97,5,17,5,641,5,17,5,257,5,17,5,193,

%T 5,17,5,257,5,17,5,274177,5,17,5,97,5,17,5,65537,5,17,5,257,5,17,5,

%U 641,5,17,5,257,5,17,5,449,5,17,5,97,5,17,5,59649589127497217

%N Smallest prime dividing 4^n + 1.

%H Max Alekseyev, <a href="/A366609/b366609.txt">Table of n, a(n) for n = 0..1983</a>

%Y Bisection of A002586.

%Y Cf. A002586, A038371, A052539, A074476, A274903, A366605, A366606, A366607, A366608, A366670, A366671, A366719.

%K nonn

%O 0,1

%A _Sean A. Irvine_, Oct 14 2023