

A292044


Wiener index of the nhalved cube graph.


0



0, 1, 6, 32, 160, 768, 3584, 16384, 73728, 327680, 1441792, 6291456, 27262976, 117440512, 503316480, 2147483648, 9126805504, 38654705664, 163208757248, 687194767360, 2886218022912, 12094627905536, 50577534877696, 211106232532992, 879609302220800, 3659174697238528
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OFFSET

1,3


COMMENTS

a(n) is the sum of the first 2^(n1) entries of A116640.  Joe Slater, Apr 11 2018


LINKS

Table of n, a(n) for n=1..26.
Eric Weisstein's World of Mathematics, Halved Cube Graph
Eric Weisstein's World of Mathematics, Wiener Index
Index entries for linear recurrences with constant coefficients, signature (8, 16).


FORMULA

a(n) = 2^(2*n5)*n for n > 1.
a(n) = 8*a(n1)  16*a(n2) for n > 3.
G.f.: ((1  2 x) x^2)/(1  4 x)^2.
a(n) = 4*a(n1) + 2^(2*n5) for n > 2.  Joe Slater, Apr 11 2018


MATHEMATICA

Table[If[n == 1, 0, 2^(2 n  5) n], {n, 40}]
Join[{0}, LinearRecurrence[{8, 16}, {1, 6}, 20]]
CoefficientList[Series[((1  2 x) x)/(1  4 x)^2, {x, 0, 20}], x]


PROG

(PARI) a(n) = if(n<2, n1, 2^(2*n5)*n); \\ Altug Alkan, Apr 12 2018


CROSSREFS

Sequence in context: A046725 A232331 A231992 * A006668 A232494 A037530
Adjacent sequences: A292041 A292042 A292043 * A292045 A292046 A292047


KEYWORD

nonn,easy


AUTHOR

Eric W. Weisstein, Sep 08 2017


STATUS

approved



