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A192791
Molecular topological index of the n-antiprism graph.
1
40, 112, 240, 448, 760, 1200, 1792, 2560, 3528, 4720, 6160, 7872, 9880, 12208, 14880, 17920, 21352, 25200, 29488, 34240, 39480, 45232, 51520, 58368, 65800, 73840, 82512, 91840, 101848, 112560, 124000, 136192, 149160, 162928, 177520, 192960, 209272, 226480, 244608, 263680
OFFSET
1,1
COMMENTS
Antiprism graphs are defined for n>=3; sequence extended to n=1 using closed form
LINKS
Eric Weisstein's World of Mathematics, Antiprism Graph
Eric Weisstein's World of Mathematics, Molecular Topological Index
FORMULA
a(n) = 4*n*(n^2 + n + 8).
a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4).
G.f.: 8*x*(4*x^2-6*x+5)/(x-1)^4. - Colin Barker, Nov 04 2012
MATHEMATICA
LinearRecurrence[{4, -6, 4, -1}, {40, 112, 240, 448}, 40] (* Harvey P. Dale, Mar 29 2018 *)
PROG
(PARI) a(n) = {4*n*(n^2 + n + 8)} \\ Andrew Howroyd, Apr 18 2021
CROSSREFS
Cf. A192838.
Sequence in context: A235301 A235291 A235893 * A345970 A235886 A261191
KEYWORD
nonn,easy
AUTHOR
Eric W. Weisstein, Jul 10 2011
EXTENSIONS
Terms a(31) and beyond from Andrew Howroyd, Apr 18 2021
STATUS
approved