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 A010724 #43 Jul 08 2025 01:44:57
%S A010724 6,8,6,8,6,8,6,8,6,8,6,8,6,8,6,8,6,8,6,8,6,8,6,8,6,8,6,8,6,8,6,8,6,8,
%T A010724 6,8,6,8,6,8,6,8,6,8,6,8,6,8,6,8,6,8,6,8,6,8,6,8,6,8,6,8,6,8,6,8,6,8,
%U A010724 6,8,6,8,6,8,6,8,6,8,6,8,6
%N A010724 Period 2: repeat (6,8).
%C A010724 Decimal expansion of 68/99. - _David A. Corneth_, Oct 18 2016
%H A010724 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (0,1).
%F A010724 a(n) = (-1)^(n+1)+7. - _Paolo P. Lava_, Oct 27 2006
%F A010724 G.f.: ( -6-8*x ) / ((x-1)*(1+x)). - _R. J. Mathar_, Nov 21 2011
%F A010724 a(0)=6, a(n) = 10 - eulerphi(a(n-1)) for n>0. - _Alexander R. Povolotsky_, Oct 16 2016
%t A010724 NestList[10 - EulerPhi@ # &, 6, 120] (* or *)
%t A010724 CoefficientList[Series[(-6 - 8 x)/((x - 1) (1 + x)), {x, 0, 120}], x] (* _Michael De Vlieger_, Oct 21 2016 *)
%o A010724 (PARI) a(n)=6+n%2*2 \\ _Charles R Greathouse IV_, Dec 08 2015
%Y A010724 Cf. A176401.
%K A010724 nonn,easy
%O A010724 0,1
%A A010724 _N. J. A. Sloane_