

A278122


a(n) = 204*2^n  248.


1



160, 568, 1384, 3016, 6280, 12808, 25864, 51976, 104200, 208648, 417544, 835336, 1670920, 3342088, 6684424, 13369096, 26738440, 53477128, 106954504, 213909256, 427818760, 855637768, 1711275784, 3422551816, 6845103880, 13690208008, 27380416264, 54760832776
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OFFSET

1,1


COMMENTS

a(n) is the first Zagreb index of the nanostar dendrimer NSC5C6[n].
The first Zagreb index of a simple connected graph is the sum of the squared degrees of its vertices. Alternately, it is the sum of the degree sums d(i)+d(j) over all edges ij of the graph. The pictorial definition of NSC5C6[n] can be viewed in the A. R. Ashrafi et al. and in the M. Rostami et al. references.
The Mpolynomial of the nanostar dendrimer NSC5C6[n] is M(NSC5C6[n],x,y) = (4*2^n  6)*x*y^3 + 4*2^n*x*y^4 + (4*2^n 6)*x^2*y^2 + (18*2^n  28)*x^2*y^3 + 2*2^n*x^2*y^4 + (7*2^n  10)*x^3*y^3 + 2^n*x^4*y^4.


LINKS



FORMULA

G.f.: 8*x*(20 + 11*x)/((1  x)*(1  2*x)).


MAPLE

seq(204*2^n248, n = 1..35);


PROG



CROSSREFS



KEYWORD

nonn,easy


AUTHOR



STATUS

approved



