A292018 Wiener index for the n-Andrásfai graph.

1, 15, 44, 88, 147, 221, 310, 414, 533, 667, 816, 980, 1159, 1353, 1562, 1786, 2025, 2279, 2548, 2832, 3131, 3445, 3774, 4118, 4477, 4851, 5240, 5644, 6063, 6497, 6946, 7410, 7889, 8383, 8892, 9416, 9955, 10509, 11078, 11662, 12261, 12875, 13504, 14148, 14807, 15481

Offset

1,2

Links

Table of n, a(n) for n=1..46.

Eric Weisstein's World of Mathematics, Andrásfai Graph

Eric Weisstein's World of Mathematics, Wiener Index

Index entries for linear recurrences with constant coefficients, signature (3,-3,1).

Formula

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

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

G.f.: (x (-1 - 12 x - 2 x^2))/(-1 + x)^3.

Mathematica

Table[(5 n - 4) (3 n - 1)/2, {n, 20}]
LinearRecurrence[{3, -3, 1}, {1, 15, 44}, 20]
CoefficientList[Series[(-1 - 12 x - 2 x^2)/(-1 + x)^3, {x, 0, 20}], x]

Crossrefs

Sequence in context: A027845 A201810 A364081 * A289669 A295980 A029827

Adjacent sequences: A292015 A292016 A292017 * A292019 A292020 A292021

Keyword

nonn,easy

Author

Eric W. Weisstein, Sep 07 2017

Status

approved