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A292018 Wiener index for the n-Andrasfai graph. 0
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

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

Eric Weisstein's World of Mathematics, Andrasfai 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: A133343 A027845 A201810 * A289669 A295980 A029827

Adjacent sequences:  A292015 A292016 A292017 * A292019 A292020 A292021

KEYWORD

nonn,easy

AUTHOR

Eric W. Weisstein, Sep 07 2017

STATUS

approved

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Last modified January 23 16:48 EST 2020. Contains 331173 sequences. (Running on oeis4.)