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 A177499 #27 Dec 12 2023 07:40:32
%S A177499 1,16,4,16,1,16,4,16,1,16,4,16,1,16,4,16,1,16,4,16,1,16,4,16,1,16,4,
%T A177499 16,1,16,4,16,1,16,4,16,1,16,4,16,1,16,4,16,1,16,4,16,1,16,4,16,1,16,
%U A177499 4,16,1,16,4,16,1,16,4,16,1,16,4,16,1,16,4,16,1,16,4,16,1,16,4,16,1,16,4,16
%N A177499 Period 4: repeat [1, 16, 4, 16].
%C A177499 From _Klaus Brockhaus_, May 14 2010: (Start)
%C A177499 Interleaving of A000012, A010855, A010709 and A010855.
%C A177499 Continued fraction expansion of (44+sqrt(2442))/88. (End)
%H A177499 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (0,0,0,1).
%F A177499 From _Klaus Brockhaus_, May 14 2010: (Start)
%F A177499 a(n+2) - a(n) = A010674(n).
%F A177499 a(n) = a(n-4) for n > 3.
%F A177499 G.f.: (1+16*x+4*x^2+16*x^3)/(1-x^4). (End)
%F A177499 a(n) = A176895(n)^2. - _Paul Curtz_, Mar 21 2011
%F A177499 a(n) = (37 - 6*cos(n*Pi/2) - 27*cos(n*Pi) - 27*I*sin(n*Pi))/4. - _Wesley Ivan Hurt_, Jul 09 2016
%p A177499 seq(op([1, 16, 4, 16]), n=0..50); # _Wesley Ivan Hurt_, Jul 09 2016
%t A177499 Table[{1, 16, 4, 16}, {21}] // Flatten (* _Jean-François Alcover_, May 24 2013 *)
%o A177499 (Magma) &cat[[1, 16, 4, 16]^^26]; // _Klaus Brockhaus_, May 14 2010
%Y A177499 Cf. A010674, A177838. [_Klaus Brockhaus_, May 14 2010]
%Y A177499 Cf. A000012, A010709, A010855, A176895.
%K A177499 nonn,easy
%O A177499 0,2
%A A177499 _Paul Curtz_, May 10 2010