A291526 a(n) = 2^n*(n - 3) + 4.

0, 0, 4, 20, 68, 196, 516, 1284, 3076, 7172, 16388, 36868, 81924, 180228, 393220, 851972, 1835012, 3932164, 8388612, 17825796, 37748740, 79691780, 167772164, 352321540, 738197508, 1543503876, 3221225476, 6710886404, 13958643716, 28991029252, 60129542148

Offset

1,3

Comments

Also the skewness of the (n+1)-hypercube graph.

Links

Table of n, a(n) for n=1..31.

Eric Weisstein's World of Mathematics, Graph Skewness

Eric Weisstein's World of Mathematics, Hypercube Graph

Index entries for linear recurrences with constant coefficients, signature (5,-8,4).

Formula

G.f.: 4*x^3/((1 - 2*x)^2*(1 - x)).

a(n) = 5*a(n-1) - 8*a(n-2) + 4*a(n-3).

a(n) = 4*A000337(n-2), with A000337(-1) = 0.

From Enrique Navarrete, Dec 10 2025: (Start)

a(n+1) = Sum_{k=1..n} A058922(k).

E.g.f.: exp(x)*((2*x - 3)*exp(x) + 4) - 1. (End)

Mathematica

Table[2^n (n - 3) + 4, {n, 20}]
LinearRecurrence[{5, -8, 4}, {0, 0, 4}, 20]
CoefficientList[Series[4 x^3/((1 - 2 x)^2 (1 - x)), {x, 0, 20}], x]

Crossrefs

Cf. A000337, A058922.

Sequence in context: A344993 A123613 A006740 * A303011 A197426 A061981

Adjacent sequences: A291523 A291524 A291525 * A291527 A291528 A291529

Keyword

nonn,easy

Author

Eric W. Weisstein, Aug 25 2017

Status

approved