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 A376901 #9 Oct 10 2024 15:40:44
%S A376901 3,2,4,5,9,12,18,23,31,38,48,57,69,80,94,107,123,138,156,173,193,212,
%T A376901 234,255,279,302,328,353,381,408,438,467,499,530,564,597,633,668,706,
%U A376901 743,783,822,864,905,949,992,1038,1083,1131,1178,1228,1277,1329,1380,1434
%N A376901 a(n) = (n*(n-1)+(-1)^n+5)/2.
%C A376901 For n >= 3, also the disorder number of the pan graph.
%H A376901 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/DisorderNumber.html">Disorder Number</a>.
%H A376901 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/PanGraph.html">Pan Graph</a>.
%H A376901 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (2,0,-2,1).
%F A376901 a(n) = 2*a(n-1)-2*a(n-3)+1*a(n-4).
%F A376901 G.f.: x*(-2+3*x^2-3*x^3)/((-1+x)^3*(1+x)).
%F A376901 After initial terms same as {A114113}+2, {A236453}+1, ({A081353}+1)/2 + 2. _Hugo Pfoertner_, Oct 10 2024.
%t A376901 Table[(n (n - 1) + 5 + (-1)^n)/2, {n, 20}]
%t A376901 LinearRecurrence[{2, 0, -2, 1}, {2, 4, 5, 9}, {0, 20}]
%Y A376901 Cf. A081353, A114113, A236453.
%K A376901 nonn,easy
%O A376901 0,1
%A A376901 _Eric W. Weisstein_, Oct 08 2024