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A192838 Molecular topological indices of the prism graphs Y_n 0
24, 84, 180, 360, 600, 972, 1428, 2064, 2808, 3780, 4884, 6264, 7800, 9660, 11700, 14112, 16728, 19764, 23028, 26760, 30744, 35244, 40020, 45360, 51000, 57252, 63828, 71064, 78648, 86940 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Prism graphs are defined for n>=3; extended to n=1 using closed form.

LINKS

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

Eric Weisstein's World of Mathematics, Molecular Topological Index

Eric Weisstein's World of Mathematics, Prism Graph

Index entries for linear recurrences with constant coefficients, signature (2,1,-4,1,2,-1).

FORMULA

a(n) = (3/2)*n*(11 + (-1)^n + 2*n*(2 + n)).

G.f.: 12*x*(x+2)*(x^3-x^2+x+1) / ( (1+x)^2*(x-1)^4 ). - R. J. Mathar, Jul 11 2011

MATHEMATICA

LinearRecurrence[{2, 1, -4, 1, 2, -1}, {24, 84, 180, 360, 600, 972,

  1428}, 20] (* Eric W. Weisstein, May 11 2017 *)

Table[3/2 n (11 + (-1)^n + 2 n (n + 2)), {n, 20}] (* Eric W. Weisstein, May 11 2017 *)

CROSSREFS

Sequence in context: A265646 A304158 A045946 * A289155 A101861 A280304

Adjacent sequences:  A192835 A192836 A192837 * A192839 A192840 A192841

KEYWORD

nonn,easy

AUTHOR

Eric W. Weisstein, Jul 11 2011

STATUS

approved

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Last modified November 15 04:00 EST 2018. Contains 317225 sequences. (Running on oeis4.)