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A224426
The hyper-Wiener index of the phenylacetylene dendrimer NSB[n], defined pictorially in the Z. Yarahmadi et al. reference.
2
68556, 2138994, 27959412, 251530740, 1844957748, 11922051060, 70741011828, 394986935412, 2107840963188, 10863256632948, 54464106804852, 267039247214196, 1285451192174196, 6093251133916788, 28507903924684404, 131887740411168372, 604241712010610292
OFFSET
0,1
COMMENTS
a(0) has been checked by the direct computation of the Wiener index (using Maple).
LINKS
FORMULA
a(n) = 116340 - 2180388*2^n + 2132604*4^n - 2299671*4^n*n/2 + 613089*4^n*n^2.
G.f.: 6*(11426+185109*x+295053*x^2+31342*x^3+600*x^4)/((1-x)*(1-2*x)*(1-4*x)^3).
MAPLE
a := proc (n) options operator, arrow: 116340-(2299671/2)*4^n*n-2180388*2^n+2132604*4^n+613089*4^n*n^2 end proc: seq(a(n), n = 0 .. 16);
MATHEMATICA
CoefficientList[Series[6 (11426 + 185109 x + 295053 x^2 + 31342 x^3 + 600 x^4) / ((1 - x) (1 - 2 x) (1 - 4 x)^3), {x, 0, 20}], x] (* Vincenzo Librandi, Jul 26 2013 *)
CROSSREFS
Cf. A224425.
Sequence in context: A205203 A205061 A093217 * A031845 A249315 A031863
KEYWORD
nonn,easy
AUTHOR
Emeric Deutsch, Apr 06 2013
STATUS
approved