

A291064


a(n) = 2^n*(n + 1)  3*(n  1).


0



4, 9, 26, 71, 180, 433, 1006, 2283, 5096, 11237, 24546, 53215, 114652, 245721, 524246, 1114067, 2359248, 4980685, 10485706, 22020039, 46137284, 96468929, 201326526, 419430331, 872415160, 1811939253, 3758096306, 7784628143, 16106127276, 33285996457
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OFFSET

1,1


COMMENTS

For n > 1, also the number of maximal irredundant sets in the nbook graph.


LINKS

Table of n, a(n) for n=1..30.
Eric Weisstein's World of Mathematics, Book Graph
Eric Weisstein's World of Mathematics, Maximal Irredundant Set
Index entries for linear recurrences with constant coefficients, signature (6, 13, 12, 4).


FORMULA

a(n) = 2^n*(n + 1)  3*(n  1).
a(n) = 6*a(n1)  13*a(n2) + 12*a(n3)  4*a(n4).
G.f.: (x (4  15 x + 24 x^2  16 x^3))/(1  3 x + 2 x^2)^2.


MATHEMATICA

Table[2^n (n + 1)  3 (n  1), {n, 20}]
LinearRecurrence[{6, 13, 12, 4}, {4, 9, 26, 71, 180}, 20]
CoefficientList[Series[(4  15 x + 24 x^2  16 x^3)/(1  3 x + 2 x^2)^2, {x, 0, 20}], x]


CROSSREFS

Sequence in context: A328657 A335983 A113682 * A145855 A240042 A099615
Adjacent sequences: A291061 A291062 A291063 * A291065 A291066 A291067


KEYWORD

nonn,easy


AUTHOR

Eric W. Weisstein, Aug 17 2017


STATUS

approved



