A278123 a(n) = 247*2^n - 300.

194, 688, 1676, 3652, 7604, 15508, 31316, 62932, 126164, 252628, 505556, 1011412, 2023124, 4046548, 8093396, 16187092, 32374484, 64749268, 129498836, 258997972, 517996244, 1035992788, 2071985876, 4143972052, 8287944404, 16575889108, 33151778516, 66303557332

Offset

1,1

Comments

a(n) is the second Zagreb index of the nanostar dendrimer NSC5C6[n].

The second Zagreb index of a simple connected graph is the sum of the degree products 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 M-polynomial 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

Table of n, a(n) for n=1..28.

A. R. Ashrafi and P. Nikzad, Szeged index of nanostar dendrimers, Digest J. of Nanomaterials and Biostructures, 4, No. 1, 2009, 155-157.

E. Deutsch and Sandi Klavzar, M-polynomial and degree-based topological indices, Iranian J. Math. Chemistry, 6, No. 2, 2015, 93-102.

M. Rostami, M. Shabanian, and H. Moghanian, Some topological indices for theoretical study of two types of nanostar dendrimers, Digest J. of Nanomaterials and Biostructures, 7, 1, 2012, 247-252.

Index entries for linear recurrences with constant coefficients, signature (3,-2).

Formula

G.f.: 2*x*(97 + 53*x)/((1 - x)*(1 - 2*x)).

Maple

seq(247*2^n-300, n = 1..35);

Prog

(Magma) [247*2^n-300: n in [1..30]]; // Vincenzo Librandi, Nov 13 2016

Crossrefs

Cf. A278122.

Sequence in context: A294578 A294595 A248549 * A158224 A205621 A205356

Adjacent sequences: A278120 A278121 A278122 * A278124 A278125 A278126

Keyword

nonn,easy

Author

Emeric Deutsch, Nov 12 2016

Status

approved