cp's OEIS Frontend

A291053 Number of maximal irredundant sets in the n-Andrásfai graph.

%I A291053 #21 Feb 16 2025 08:33:50
%S A291053 2,10,28,88,217,493,989,1794,3016,4785,7256,10612,15067,20869,28303,
%T A291053 37694,49410,63865,81522,102896,128557,159133,195313,237850,287564,
%U A291053 345345,412156,489036,577103,677557,791683,920854,1066534,1230281,1413750,1618696,1846977,2100557
%N A291053 Number of maximal irredundant sets in the n-Andrásfai graph.
%H A291053 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/AndrasfaiGraph.html">Andrásfai Graph</a>
%H A291053 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/MaximalIrredundantSet.html">Maximal Irredundant Set</a>
%H A291053 <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (6, -15, 20, -15, 6, -1).
%F A291053 From _Eric W. Weisstein_, Aug 21 2017: (Start)
%F A291053 a(n) = (-3120 + 10932*n - 4970*n^2 + 765*n^3 - 10*n^4 + 3*n^5)/120 for n > 3.
%F A291053 a(n) = 6*a(n-1) - 15*a(n-2) + 20*a(n-3) - 15*a(n-4) + 6*a(n-5) - a(n-6) for n > 9.
%F A291053 G.f.: (x (2 - 2 x - 2 x^2 + 30 x^3 - 61 x^4 + 89 x^5 - 112 x^6 + 77 x^7 - 18 x^8))/(-1 + x)^6.
%F A291053 (End)
%t A291053 Table[Piecewise[{{2, n == 1}, {10, n == 2}, {28, n == 3}}, (-3120 + 10932 n - 4970 n^2 + 765 n^3 - 10 n^4 + 3 n^5)/120], {n, 20}]
%t A291053 Join[{2, 10, 28}, LinearRecurrence[{6, -15, 20, -15, 6, -1}, {88, 217, 493, 989, 1794, 3016}, 20]] (* _Eric W. Weisstein_, Aug 21 2017 *)
%t A291053 CoefficientList[Series[(2 - 2 x - 2 x^2 + 30 x^3 - 61 x^4 + 89 x^5 - 112 x^6 + 77 x^7 - 18 x^8)/(-1 + x)^6, {x, 0, 20}], x] (* _Eric W. Weisstein_, Aug 21 2017 *)
%Y A291053 Cf. A285272, A290587, A291053.
%K A291053 nonn
%O A291053 1,1
%A A291053 _Eric W. Weisstein_, Aug 17 2017
%E A291053 a(9)-a(20) from _Andrew Howroyd_, Aug 19 2017
%E A291053 a(21) and above from _Eric W. Weisstein_, Aug 21 2017