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 A286567 #13 Sep 23 2018 16:39:02
%S A286567 1,1,3,5,11,3,43,5,3,11,683,3,2731,43,3,5,43691,3,174763,5,3,23,
%T A286567 2796203,3,11,2731,3,5,59,3,715827883,5,3,43691,11,3,1777,174763,3,5,
%U A286567 83,3,2932031007403,5,3,47,283,3,43,11,3,5,107,3,11,5,3,59,2833,3,768614336404564651,715827883,3,5,11,3,7327657,5,3,11,56409643,3,1753,223,3,5,43,3
%N A286567 Smallest prime factor of the n-th Jacobsthal number: a(n) = A020639(A001045(n)), with a(1)=a(2)=1.
%H A286567 Hans Havermann, <a href="/A286567/b286567.txt">Table of n, a(n) for n = 1..1122</a>
%F A286567 a(n) = A020639(A001045(n)).
%t A286567 Rest[FactorInteger[#][[1,1]]&/@LinearRecurrence[{1,2},{0,1},100]] (* _Harvey P. Dale_, Sep 23 2018 *)
%o A286567 (Scheme) (define (A286567 n) (A020639 (A001045 n)))
%Y A286567 Cf. A001045, A020639, A278165.
%K A286567 nonn
%O A286567 1,3
%A A286567 _Antti Karttunen_ & _Hans Havermann_, May 21 2017