OFFSET
0,1
LINKS
Harvey P. Dale, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (10, -20).
FORMULA
a(n) = 10*a(n-1) - 20*a(n-2) for n > 1; a(0) = 2, a(1) = 15.
G.f.: (2-5*x)/(1-10*x+20*x^2).
MATHEMATICA
LinearRecurrence[{10, -20}, {2, 15}, 30] (* Harvey P. Dale, Dec 24 2012 *)
PROG
(Magma) Z<x>:=PolynomialRing(Integers()); N<r>:=NumberField(x^2-5); S:=[ ((2+r)*(5+r)^n+(2-r)*(5-r)^n)/2: n in [0..19] ]; [ Integers()!S[j]: j in [1..#S] ]; // Klaus Brockhaus, Jul 19 2009
CROSSREFS
KEYWORD
nonn
AUTHOR
Al Hakanson (hawkuu(AT)gmail.com), Jul 13 2009
EXTENSIONS
Edited and extended beyond a(5) by Klaus Brockhaus, Jul 19 2009
Formulae corrected and clarified by Harvey P. Dale, Dec 24 2012
STATUS
approved