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A292542 Number of 4-cycles in the n-Sierpinski tetrahedron graph. 3
3, 39, 156, 624, 2496, 9984, 39936, 159744, 638976, 2555904, 10223616, 40894464, 163577856, 654311424, 2617245696, 10468982784, 41875931136, 167503724544, 670014898176, 2680059592704, 10720238370816, 42880953483264, 171523813933056, 686095255732224 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..24.

Eric Weisstein's World of Mathematics, Graph Cycle

Eric Weisstein's World of Mathematics, Sierpinski Tetrahedron Graph

Index entries for linear recurrences with constant coefficients, signature (4).

FORMULA

a(n) = 39*4^(n - 2) for n > 1.

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

G.f.: -3*x*(1 + 9*x)/(-1 + 4*x).

MATHEMATICA

Table[If[n == 1, 3, 39 4^(n - 1)], {n, 30}]

Join[{3}, LinearRecurrence[{4}, {39}, 20]]

CoefficientList[Series[-3 (1 + 9 x)/(-1 + 4 x), {x, 0, 20}], x]

CROSSREFS

Cf. A292540 (3-cycles), A292543 (5-cycles), A292545 (6-cycles).

Sequence in context: A153875 A082954 A209366 * A212664 A050392 A292294

Adjacent sequences:  A292539 A292540 A292541 * A292543 A292544 A292545

KEYWORD

nonn,easy

AUTHOR

Eric W. Weisstein, Sep 18 2017

STATUS

approved

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Last modified May 25 22:17 EDT 2019. Contains 323576 sequences. (Running on oeis4.)