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 A176895 #34 Dec 12 2023 07:40:22
%S A176895 1,4,2,4,1,4,2,4,1,4,2,4,1,4,2,4,1,4,2,4,1,4,2,4,1,4,2,4,1,4,2,4,1,4,
%T A176895 2,4,1,4,2,4,1,4,2,4,1,4,2,4,1,4,2,4,1,4,2,4,1,4,2,4,1,4,2,4,1,4,2,4,
%U A176895 1,4,2,4,1,4,2,4,1,4,2,4,1,4,2,4,1,4,2,4,1,4,2,4,1,4,2,4,1,4,2,4,1,4,2,4,1
%N A176895 Period 4: repeat [1, 4, 2, 4].
%H A176895 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (0,0,0,1).
%F A176895 a(n) = 4/gcd(n,4). - _Michael Somos_, Jan 06 2011
%F A176895 a(n) = 4-(1+(-1)^n)*(5+I^n)/4. - _Bruno Berselli_, Mar 22 2011
%F A176895 G.f.: ( 1+4*x+2*x^2+4*x^3 ) / ( (1-x)*(1+x)*(x^2+1) ). - _R. J. Mathar_, Mar 21 2011
%F A176895 From _Wesley Ivan Hurt_, Jul 11 2016: (Start)
%F A176895 a(n) = a(n-4) for n>3.
%F A176895 a(n) = 2^((5-(-I)^n-I^n-3*I^(2*n))/4) where I=sqrt(-1). (End)
%p A176895 seq(op([1, 4, 2, 4]), n=0..50); # _Wesley Ivan Hurt_, Jul 11 2016
%t A176895 PadRight[{}, 100, {1, 4, 2, 4}] (* _Wesley Ivan Hurt_, Jul 11 2016 *)
%o A176895 (PARI) a(n)=4/gcd(n,4) \\ _Charles R Greathouse IV_, Oct 07 2015
%o A176895 (Magma) &cat [[1, 4, 2, 4]^^30]; // _Wesley Ivan Hurt_, Jul 11 2016
%Y A176895 Cf. A056594.
%K A176895 nonn,easy
%O A176895 0,2
%A A176895 _Paul Curtz_, Apr 28 2010