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A277986
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a(n) = 74*n - 14.
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1
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-14, 60, 134, 208, 282, 356, 430, 504, 578, 652, 726, 800, 874, 948, 1022, 1096, 1170, 1244, 1318, 1392, 1466, 1540, 1614, 1688, 1762, 1836, 1910, 1984, 2058, 2132, 2206, 2280, 2354, 2428, 2502, 2576, 2650, 2724, 2798, 2872, 2946, 3020, 3094, 3168
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OFFSET
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0,1
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COMMENTS
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For n >= 1, a(n) is the first Zagreb index of the tetrameric 1,3-adamantane TA[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 the tetrameric 1,3-adamantane can be viewed in the G. H. Fath-Tabar et al. reference.
The M-polynomial of the tetrameric 1,3-adamantane TA[n] is M(TA[n], x, y) = 6*(n+1)*x^2*y^3 + 6*(n-1)*x^2*y^4 + (n-1)*x^4*y^4.
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LINKS
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FORMULA
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G.f.: 2*(44*x - 7)/(1-x)^2.
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MAPLE
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seq(74*n-14, n = 0..40);
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MATHEMATICA
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PROG
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CROSSREFS
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KEYWORD
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sign,easy
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AUTHOR
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STATUS
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approved
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