

A278131


a(n) = 591*2^n  273.


1



318, 909, 2091, 4455, 9183, 18639, 37551, 75375, 151023, 302319, 604911, 1210095, 2420463, 4841199, 9682671, 19365615, 38731503, 77463279, 154926831, 309853935, 619708143, 1239416559, 2478833391, 4957667055, 9915334383, 19830669039, 39661338351
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OFFSET

0,1


COMMENTS

a(n) is the second Zagreb index of the phenylazomethine dendrimer G[n] defined pictorially in the Yarahmadi references. 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 Mpolynomial of the dendrimer NSB[n] is M(NSB[n], x, y) = 9*2^n*x*y^4 + (24*2^n  12)*x^2*y^2 + (48*2^n 24)*x^2*y^3 +(15*2^n9)*x^3*y^3+3*2^n*x^3*y^4.


LINKS



FORMULA

O.g.f.: 3*(106  15*x)/((1  x)*(1  2*x)).
E.g.f.: 3*(91 + 197*exp(x))*exp(x).
a(n) = 3*a(n1)  2*a(n2).


MAPLE

seq(591*2^n273, n=0..35);


MATHEMATICA



PROG



CROSSREFS



KEYWORD

nonn,easy


AUTHOR



EXTENSIONS



STATUS

approved



