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A292540 Number of 3-cycles in the n-Sierpinski tetrahedron graph. 3

%I

%S 4,20,80,320,1280,5120,20480,81920,327680,1310720,5242880,20971520,

%T 83886080,335544320,1342177280,5368709120,21474836480,85899345920,

%U 343597383680,1374389534720,5497558138880,21990232555520,87960930222080,351843720888320,1407374883553280

%N Number of 3-cycles in the n-Sierpinski tetrahedron graph.

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/GraphCycle.html">Graph Cycle</a>

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/SierpinskiTetrahedronGraph.html">Sierpinski Tetrahedron Graph</a>

%H <a href="/index/Rec#order_01">Index entries for linear recurrences with constant coefficients</a>, signature (4).

%F a(n) = 5*4^(n - 1) for n > 1.

%F a(n) = 4*a(n-1) for n > 2.

%F G.f. -4*x*(1 + x)/(-1 + 4 x).

%t Table[If[n == 1, 4, 5 4^(n - 1)], {n, 10}]

%t Join[{4}, LinearRecurrence[{4}, {20}, 30]]

%t CoefficientList[Series[-((4 (1 + x))/(-1 + 4 x)), {x, 0, 20}], x]

%Y Cf. A003947, A269696.

%Y Cf. A292542 (4-cycles), A292543 (5-cycles), A292545 (6-cycles).

%K nonn

%O 1,1

%A _Eric W. Weisstein_, Sep 18 2017

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Last modified May 26 17:38 EDT 2019. Contains 323597 sequences. (Running on oeis4.)