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 A308350 #15 May 28 2025 20:58:11
%S A308350 21,24,135,16,448,96,1620,64,4400,384,13104,256,32640,1536,88128,1024,
%T A308350 209152,6144,532224,4096,1224704,24576,2995200,16384,6746112,98304,
%U A308350 16035840,65536,35553280,393216,82722816,262144,181207040,1572864,414646272,1048576,899678208,6291456
%N A308350 Number of maximum irredundant sets in the n-web graph.
%H A308350 Andrew Howroyd, <a href="/A308350/b308350.txt">Table of n, a(n) for n = 3..1000</a>
%H A308350 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/MaximumIrredundantSet.html">Maximum Irredundant Vertex Set</a>.
%H A308350 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/WebGraph.html">Web Graph</a>.
%H A308350 <a href="/index/Rec#order_10">Index entries for linear recurrences with constant coefficients</a>, signature (0,2,0,8,0,-16,0,-16,0,32).
%F A308350 From _Andrew Howroyd_, May 28 2025: (Start)
%F A308350 G.f.: x^3*(21 + 24*x + 93*x^2 - 32*x^3 + 10*x^4 - 128*x^5 - 20*x^6 + 128*x^7 + 72*x^8 + 128*x^9)/((1 - 2*x^2)^3*(1 + 2*x^4)^2).
%F A308350 a(4*n) = 6*4^n; a(4*n+1) = 9*(4*n + 1)*(2*n + 1)*4^(n-1); a(4*n+2) = 4*4^n; a(4*n+3) = (4*n + 3)*(9*n + 7)*4^n. (End)
%o A308350 (PARI) a(n)={my(m=n\4); 4^m*if(n%2, if(n%4==1, 9*(4*m + 1)*(2*m + 1)/4, (4*m + 3)*(9*m + 7)), if(n%4==0, 6, 4))} \\ _Andrew Howroyd_, May 28 2025
%Y A308350 Cf. A290591, A291105.
%K A308350 nonn,easy
%O A308350 3,1
%A A308350 _Eric W. Weisstein_, May 21 2019
%E A308350 a(10) from _Eric W. Weisstein_, Jun 10 2021
%E A308350 a(11) onwards from _Andrew Howroyd_, May 28 2025