

A277108


a(n) = 4n*(n+5).


1



24, 56, 96, 144, 200, 264, 336, 416, 504, 600, 704, 816, 936, 1064, 1200, 1344, 1496, 1656, 1824, 2000, 2184, 2376, 2576, 2784, 3000, 3224, 3456, 3696, 3944, 4200, 4464, 4736, 5016, 5304, 5600, 5904, 6216, 6536, 6864, 7200
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OFFSET

1,1


COMMENTS

a(n) is the second Zagreb index of the helm graph H[n] (n>=3).
The second Zagreb index of a simple connected graph g is the sum of the degree products d(i)d(j) over all edges ij of g.
The Mpolynomial of the Helm graph H[n] is M(H[n]; x,y) = n*x*y^4 + n*x^4*y^4 + n*x^4*y^n.  Emeric Deutsch, May 11 2018
The helm graph H[n] is the graph obtained from an nwheel graph by adjoining a pendant edge at each node of the cycle.  Emeric Deutsch, May 11 2018


LINKS



FORMULA

G.f.: G(z) = 8z(32z)/(1z)^3.


MAPLE

seq(4*n^2+20*n, n = 1 .. 40);


MATHEMATICA

Table[4 n (n + 5), {n, 40}] (* or *)
Rest@ CoefficientList[Series[8 x (3  2 x)/(1  x)^3, {x, 0, 40}], x] (* Michael De Vlieger, Nov 06 2016 *)


PROG



CROSSREFS



KEYWORD

nonn,easy


AUTHOR



STATUS

approved



