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 A341307 #21 Nov 27 2023 04:22:15
%S A341307 1,0,1,1,2,2,3,2,3,3,4,4,5,4,5,5,6,6,7,6,7,7,8,8,9,8,9,9,10,10,11,10,
%T A341307 11,11,12,12,13,12,13,13,14,14,15,14,15,15,16,16,17,16,17,17,18,18,19,
%U A341307 18,19,19,20,20,21,20,21,21,22,22,23,22,23,23,24,24,25,24,25,25,26,26
%N A341307 Expansion of (x^9+x^8+2*x^7+x^6+2*x^5+2*x^4+x^3+x^2+1)/(1-x^6)^2.
%H A341307 Masao Koike, <a href="https://oeis.org/A004016/a004016.pdf">Modular forms on non-compact arithmetic triangle groups</a>, Unpublished manuscript [Extensively annotated with OEIS A-numbers by N. J. A. Sloane, Feb 14 2021. I wrote 2005 on the first page but the internal evidence suggests 1997.] See page 13, top of page.
%H A341307 <a href="/index/Rec#order_07">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,0,0,0,1,-1).
%F A341307 G.f.: (x^9+x^8+2*x^7+x^6+2*x^5+2*x^4+x^3+x^2+1)/(1-x^6)^2 = (1-x+x^2+x^4)/(( x-1)^2*(x+1)*(1+x+x^2)*(1-x+x^2)).
%F A341307 From _Wesley Ivan Hurt_, May 03 2021: (Start)
%F A341307 a(n) = floor((n+2+(-1)^n)/3).
%F A341307 a(n) = a(n-1)+a(n-6)-a(n-7). (End)
%F A341307 a(n) = A103469(n), n>=3. - _R. J. Mathar_, Nov 27 2023
%t A341307 CoefficientList[Series[(x^9+x^8+2*x^7+x^6+2*x^5+2*x^4+x^3+x^2+1)/(1-x^6)^2,{x,0,300}],x] (* _Vincenzo Librandi_, Mar 07 2021 *)
%Y A341307 Cf. A341311.
%K A341307 nonn,easy
%O A341307 0,5
%A A341307 _N. J. A. Sloane_, Feb 14 2021