|
|
A180222
|
|
a(n) = 4*a(n-1) + 8*a(n-2), with a(1)=0 and a(2)=1.
|
|
14
|
|
|
0, 1, 4, 24, 128, 704, 3840, 20992, 114688, 626688, 3424256, 18710528, 102236160, 558628864, 3052404736, 16678649856, 91133837312, 497964548096, 2720928890880, 14867431948288, 81237158920192, 443888091267072, 2425449636429824, 13252903275855872
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,3
|
|
LINKS
|
|
|
FORMULA
|
a(n) = 2^(n-3)*((1+sqrt(3))^(n-1)-(1-sqrt(3))^(n-1))/sqrt(3). - Rolf Pleisch, May 14 2011
G.f.: x^2/(1-4*x-8*x^2).
|
|
MATHEMATICA
|
Join[{a=0, b=1}, Table[c=4*b+8*a; a=b; b=c, {n, 100}]]
LinearRecurrence[{4, 8}, {0, 1}, 30] (* G. C. Greubel, Jan 16 2018 *)
|
|
PROG
|
(Magma) I:=[0, 1]; [n le 2 select I[n] else 4*Self(n-1) + 8*Self(n-2): n in [1..30]]; // G. C. Greubel, Jan 16 2018
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,easy
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|