A227494 The Wiener index of the nanostar dendrimer D_n, defined pictorially as NS[n] in the Yang et al. reference.

1437, 18915, 170799, 1224231, 7577943, 42506295, 222662391, 1110797943, 5346791799, 25055240055, 115015961463, 519520043895, 2316518945655, 10221182047095, 44708102116215, 194132294964087, 837742493569911, 3595852736893815

Offset

0,1

Comments

a(2) has been checked by the direct computation of the Wiener index (using Maple).

References

L. Yang, Connectivity, PI and vertex-Pi indices and polynomials of an infinite class of dendrimer nanostars, International J. Physical Sciences, 7(9), 2012, 1420-1423.

Links

Table of n, a(n) for n=0..17.

Formula

a(n) = 4983 + 2^n*(15048*n + 29502) + 4^n*(14256*n - 33048).

G.f.: 3*(479 + 78*x + 5624*x^2 + 576*x^3 + 8192*x^4)/((1-x)*(1-2*x)^2*(1-4*x)^2).

Maple

a := proc (n) options operator, arrow: 4983+2^n*(15048*n+29502)+4^n*(14256*n-33048) end proc: seq(a(n), n = 0 .. 20);

Crossrefs

Cf. A227495.

Sequence in context: A245948 A221004 A204862 * A352249 A351677 A101798

Adjacent sequences: A227491 A227492 A227493 * A227495 A227496 A227497

Keyword

nonn,easy

Author

Emeric Deutsch, Jul 17 2013

Status

approved