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 A289121 #30 Feb 16 2025 08:33:48
%S A289121 3,4,5,12,37,98,219,430,767,1272,1993,2984,4305,6022,8207,10938,14299,
%T A289121 18380,23277,29092,35933,43914,53155,63782,75927,89728,105329,122880,
%U A289121 142537,164462,188823,215794,245555,278292,314197,353468,396309,442930,493547,548382,607663
%N A289121 a(n) = (8 - 2*n + 11*n^2 - 6*n^3 + n^4)/4.
%C A289121 For n > 1, number of maximal irredundant sets in the n-crown graph.
%H A289121 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/CrownGraph.html">Crown Graph</a>
%H A289121 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/MaximalIrredundantSet.html">Maximal Irredundant Set</a>
%H A289121 <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (5,-10,10,-5,1).
%F A289121 a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5).
%F A289121 G.f.: x*(3 - 11*x + 15*x^2 - 3*x^3 + 2*x^4)/(1 - x)^5.
%F A289121 E.g.f.: (1/4)*((8 + 4*x + x^4)*exp(x) - 8). - _G. C. Greubel_, Aug 17 2017
%t A289121 Table[(8 - 2 n + 11 n^2 - 6 n^3 + n^4)/4, {n, 20}]
%t A289121 LinearRecurrence[{5, -10, 10, -5, 1}, {3, 4, 5, 12, 37}, 20]
%t A289121 CoefficientList[Series[(-3 + 11 x - 15 x^2 + 3 x^3 - 2 x^4)/(-1 + x)^5, {x, 0, 20}], x]
%o A289121 (PARI) x='x+O('x^50); Vec(x*(3 - 11*x + 15*x^2 - 3*x^3 + 2*x^4)/(1 - x)^5) \\ _G. C. Greubel_, Aug 17 2017
%o A289121 (Magma) [(8 - 2*n + 11*n^2 - 6*n^3 + n^4)/4 : n in [1..50]]; // _Wesley Ivan Hurt_, Dec 02 2021
%K A289121 nonn,easy
%O A289121 1,1
%A A289121 _Eric W. Weisstein_, Aug 17 2017