A192790 Molecular topological index of the Andrasfai graphs

4, 80, 336, 880, 1820, 3264, 5320, 8096, 11700, 16240, 21824, 28560, 36556, 45920, 56760, 69184, 83300, 99216, 117040, 136880, 158844, 183040, 209576, 238560, 270100, 304304, 341280, 381136, 423980, 469920

Offset

1,1

Links

Table of n, a(n) for n=1..30.

Eric Weisstein's World of Mathematics, Molecular Topological Index

Index entries for linear recurrences with constant coefficients, signature (4,-6,4,-1).

Formula

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

a(n) = 4*A006566(n).

a(n) = +4*a(n-1) -6*a(n-2) +4*a(n-3) -1*a(n-4).

G.f.: 4*x*(1+16*x+10*x^2) / (x-1)^4 . - R. J. Mathar, May 06 2014

Mathematica

LinearRecurrence[{4, -6, 4, -1}, {4, 80, 336, 880}, 30] (* Harvey P. Dale, Jan 31 2013 *)

Crossrefs

Sequence in context: A216410 A125710 A204296 * A211152 A093854 A345459

Adjacent sequences: A192787 A192788 A192789 * A192791 A192792 A192793

Keyword

nonn,easy

Author

Eric W. Weisstein, Jul 10 2011

Status

approved