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 A197916 #19 Jul 30 2019 18:52:13
%S A197916 0,1,6,7,2,3,8,9,4,5,10,11,6,7,12,13,8,9,14,15,10,11,16,17,12,13,18,
%T A197916 19,14,15,20,21,16,17,22,23,18,19,24,25,20,21,26,27,22,23,28,29,24,25,
%U A197916 30,31,26,27,32,33,28,29,34,35,30,31,36,37,32,33,38,39
%N A197916 Related to the periodic sequence A171654.
%C A197916 All numbers appear twice except numbers 0,1,2,3,4,5 which appear once. - From A. Salagnad, Oct 19 2011.
%H A197916 <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,0,1,-1).
%F A197916 a(n)=A171654(n) mod 10.
%F A197916 a(n)=Sum_k>=0 {A030308(n,k)*b(k)} with b(0)=1, b(1)=6 and b(k)=2^(k-1) for k>1.
%F A197916 G.f. ( -x*(-1-5*x-x^2+5*x^3) ) / ( (1+x)*(1+x^2)*(x-1)^2 ). - R. J. Mathar, Oct 20 2011
%F A197916 a(n) = n/2+(11-(-1)^n)/4 -5*A057077(n)/2. - R. J. Mathar, Oct 20 2011
%t A197916 LinearRecurrence[{1,0,0,1,-1},{0,1,6,7,2},80] (* _Harvey P. Dale_, Jul 30 2019 *)
%o A197916 (PARI) a(n)=([0,1,0,0,0; 0,0,1,0,0; 0,0,0,1,0; 0,0,0,0,1; -1,1,0,0,1]^n*[0;1;6;7;2])[1,1] \\ _Charles R Greathouse IV_, Jul 06 2017
%Y A197916 Cf. A171654.
%K A197916 easy,nonn
%O A197916 0,3
%A A197916 _Philippe Deléham_, Oct 19 2011