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 A066530 #23 Jan 31 2023 08:30:50
%S A066530 1,2,2,3,4,5,5,6,7,8,8,9,10,11,11,12,13,14,14,15,16,17,17,18,19,20,20,
%T A066530 21,22,23,23,24,25,26,26,27,28,29,29,30,31,32,32,33,34,35,35,36,37,38,
%U A066530 38,39,40,41,41,42,43,44,44,45,46,47,47,48,49,50,50,51,52,53,53,54,55
%N A066530 Expansion of (1+x+x^3)/((1-x)*(1-x^4)).
%H A066530 <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,0,1,-1).
%F A066530 G.f.: (1 + x + x^3)/((1 - x)*(1 - x^4)).
%F A066530 a(n) = floor((3*n + 5)/4).
%F A066530 a(n) = a(n-1) + a(n-4) - a(n-5) for n>4, with a(0)=1, a(1)=2, a(2)=2, a(3)=3, a(4)=4. - _Harvey P. Dale_, Apr 01 2013
%F A066530 a(n) = (6*n+7+2*cos(n*Pi/2)+cos((n+1)*Pi)+2*sin(n*Pi/2))/8. - _Wesley Ivan Hurt_, Oct 01 2017
%F A066530 Sum_{n>=0} (-1)^n/a(n) = log(3)/2 + Pi/(6*sqrt(3)). - _Amiram Eldar_, Jan 31 2023
%p A066530 A066530:=n->floor((3*n+5)/4): seq(A066530(n), n=0..100); # _Wesley Ivan Hurt_, Jan 02 2017
%t A066530 CoefficientList[ Series[ (1 + x + x^3)/((1 - x)*(1 - x^4)), {x, 0, 75} ], x] (* or *) Table[Floor[(3 n + 5)/4], {n, 0, 75}]
%t A066530 LinearRecurrence[{1, 0, 0, 1, -1}, {1, 2, 2, 3, 4}, 80] (* _Harvey P. Dale_, Apr 01 2013 *)
%o A066530 (Magma) [Floor((3*n + 5)/4): n in [0..100]]; // _Wesley Ivan Hurt_, Jan 02 2017
%Y A066530 Cf. A037915.
%K A066530 nonn,easy
%O A066530 0,2
%A A066530 _Robert G. Wilson v_, Jan 06 2002