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A305265 a(n) = 12*2^n + 62. 4
74, 86, 110, 158, 254, 446, 830, 1598, 3134, 6206, 12350, 24638, 49214, 98366, 196670, 393278, 786494, 1572926, 3145790, 6291518, 12582974, 25165886, 50331710, 100663358, 201326654, 402653246, 805306430, 1610612798, 3221225534, 6442451006, 12884901950, 25769803838, 51539607614, 103079215166, 206158430270 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,1
COMMENTS
a(n) (n>=1) is the number of vertices of the first type of dendrimer nanostar G[n], shown pictorially in the Iranmanesh et al. reference (Fig. 1).
LINKS
A. Iranmanesh, N. A. Gholami, Computing the Szeged index of two type dendrimer nanostars, Croatica Chemica Acta, 81, No. 2, 2008, 299-303.
FORMULA
From Colin Barker, May 30 2018: (Start)
G.f.: 2*(37 - 68*x) / ((1 - x)*(1 - 2*x)).
a(n) = 3*a(n-1) - 2*a(n-2) for n>1.
(End)
MAPLE
seq(12*2^n+62, n = 0..40);
MATHEMATICA
Table[12*2^n+62, {n, 0, 50}] (* or *) LinearRecurrence[{3, -2}, {74, 86}, 50] (* Harvey P. Dale, Jun 23 2020 *)
PROG
(PARI) Vec(2*(37 - 68*x) / ((1 - x)*(1 - 2*x)) + O(x^40)) \\ Colin Barker, May 30 2018
CROSSREFS
Sequence in context: A136948 A137139 A095569 * A055111 A020203 A295158
KEYWORD
nonn,easy
AUTHOR
Emeric Deutsch, May 29 2018
STATUS
approved

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Last modified March 29 11:45 EDT 2024. Contains 371278 sequences. (Running on oeis4.)