|
|
A304383
|
|
a(n) = 36*2^n - 5 (n>=1).
|
|
2
|
|
|
67, 139, 283, 571, 1147, 2299, 4603, 9211, 18427, 36859, 73723, 147451, 294907, 589819, 1179643, 2359291, 4718587, 9437179, 18874363, 37748731, 75497467, 150994939, 301989883, 603979771, 1207959547, 2415919099, 4831838203, 9663676411, 19327352827, 38654705659, 77309411323
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
COMMENTS
|
a(n) is the number of edges in the molecular graph NS2[n], defined pictorially in the Ashrafi et al. reference (Fig. 2, where NS2[2] is shown).
|
|
LINKS
|
|
|
FORMULA
|
G.f.: x*(67 - 62*x) / ((1 - x)*(1 - 2*x)).
a(n) = 3*a(n-1) - 2*a(n-2) for n>2.
(End)
|
|
MAPLE
|
seq(36*2^n-5, n = 1 .. 40);
|
|
PROG
|
(PARI) Vec(x*(67 - 62*x) / ((1 - x)*(1 - 2*x)) + O(x^40)) \\ Colin Barker, May 14 2018
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,easy
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|