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 A290699 #14 Feb 16 2025 08:33:50
%S A290699 0,2,6,14,28,52,94,170,312,584,1114,2158,4228,8348,16566,32978,65776,
%T A290699 131344,262450,524630,1048956,2097572,4194766,8389114,16777768,
%U A290699 33555032,67109514,134218430,268436212,536871724,1073742694,2147484578,4294968288,8589935648,17179870306
%N A290699 a(n) = 2^n - n + n^2.
%C A290699 Number of minimal edge covers in the n-book graph.
%H A290699 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/BookGraph.html">Book Graph</a>
%H A290699 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/MinimalEdgeCover.html">Minimal Edge Cover</a>
%H A290699 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (5, -9, 7, -2).
%F A290699 a(n) = 2*A132109(n-1).
%F A290699 a(n) = 5*a(n-1) - 9*a(n-2) + 7*a(n-3) - 2*a(n-4).
%F A290699 G.f.: -((2 x (-1 + 2 x - x^2 + x^3))/((-1 + x)^3 (-1 + 2 x))).
%t A290699 Table[2^n - n + n^2, {n, 20}]
%t A290699 LinearRecurrence[{5, -9, 7, -2}, {2, 6, 14, 28}, 20]
%t A290699 CoefficientList[Series[-((2 (-1 + 2 x - x^2 + x^3))/((-1 + x)^3 (-1 + 2 x))), {x, 0, 20}], x]
%Y A290699 Cf. A132109.
%Y A290699 A077265 is a subsequence.
%K A290699 nonn,easy
%O A290699 0,2
%A A290699 _Eric W. Weisstein_, Aug 09 2017
%E A290699 Added a(0)=0. - _N. J. A. Sloane_, May 25 2019