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 A385869 #17 Jul 16 2025 22:30:58
%S A385869 1,4,7,12,17,24,27,32,37,44,47,52,57,64,67,72,77,84,87,92,97,104,107,
%T A385869 112,117,124,127,132,137,144,147,152,157,164,167,172,177,184,187,192,
%U A385869 197,204,207,212,217,224,227,232,237,244,247,252,257,264,267,272,277,284,287,292,297
%N A385869 The maximum possible number of 7-cycles in an outerplanar graph on n vertices.
%H A385869 <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,0,1,-1).
%F A385869 For n >= 2, a(4n) = 20n-36, a(4n+1) = 20n-33, a(4n+2) = 20n-28, a(4n+3) = 20n-23.
%F A385869 For n >= 8, a(n) = 5n - 36 - 2sgn(mod(n,4))
%F A385869 Excluding a(7), the first differences are 4-periodic: 3,5,5,7,3,5,5,7,...
%F A385869 G.f.: x^7*(4*x^5+4*x^4+5*x^3+3*x^2+3*x+1)/((x+1)*(x^2+1)*(x-1)^2). - _Alois P. Heinz_, Jul 15 2025
%t A385869 Drop[CoefficientList[Series[x^7*(4*x^5+4*x^4+5*x^3+3*x^2+3*x+1)/((x+1)*(x^2+1)*(x-1)^2),{x,0,67}],x],7] (* _James C. McMahon_, Jul 16 2025 *)
%K A385869 nonn,easy
%O A385869 7,2
%A A385869 _Stephen Bartell_, Jul 10 2025