OFFSET
0,1
LINKS
FORMULA
a(n) = 8*a(n-1) - 13*a(n-2) for n > 1; a(0) = 2, a(1) = 11.
G.f.: (2-5*x)/(1-8*x+13*x^2).
MAPLE
a := proc (n) options operator, arrow; expand((1/2)*(2+sqrt(3))*(4+sqrt(3))^n+(1/2)*(2-sqrt(3))*(4-sqrt(3))^n) end proc: seq(a(n), n = 0 .. 20); # Emeric Deutsch, Jul 09 2009
PROG
(Magma) Z<x>:=PolynomialRing(Integers()); N<r>:=NumberField(x^2-3); S:=[ ((2+r)*(4+r)^n+(2-r)*(4-r)^n)/2: n in [0..21] ]; [ Integers()!S[j]: j in [1..#S] ]; // Klaus Brockhaus, Jul 05 2009
CROSSREFS
KEYWORD
nonn
AUTHOR
Al Hakanson (hawkuu(AT)gmail.com), Jun 29 2009
EXTENSIONS
Edited and extended beyond a(5) by Klaus Brockhaus, Jul 05 2009
STATUS
approved