A163609 a(n) = ((5 + 2*sqrt(2))*(3 + sqrt(2))^n + (5 - 2*sqrt(2))*(3 - sqrt(2))^n)/2.
5, 19, 79, 341, 1493, 6571, 28975, 127853, 564293, 2490787, 10994671, 48532517, 214232405, 945666811, 4174374031, 18426576509, 81338840837, 359047009459, 1584910170895, 6996131959157, 30882420558677, 136321599637963
Offset: 0
Links
- G. C. Greubel, Table of n, a(n) for n = 0..1000
- Index entries for linear recurrences with constant coefficients, signature (6,-7).
Programs
-
Magma
Z
:= PolynomialRing(Integers()); N :=NumberField(x^2-2); S:=[ ((5+2*r)*(3+r)^n+(5-2*r)*(3-r)^n)/2: n in [0..21] ]; [ Integers()!S[j]: j in [1..#S] ]; // Klaus Brockhaus, Aug 06 2009 -
Mathematica
LinearRecurrence[{6, -7}, {5, 19}, 50] (* G. C. Greubel, Jul 29 2017 *)
-
PARI
x='x+O('x^50); Vec((5-11*x)/(1-6*x+7*x^2)) \\ G. C. Greubel, Jul 29 2017
Formula
a(n) = 6*a(n-1) - 7*a(n-2) for n > 1; a(0) = 5, a(1) = 19.
G.f.: (5-11*x)/(1-6*x+7*x^2).
E.g.f.: exp(3*x)*( 5*cosh(sqrt(2)*x) + 2*sqrt(2)*sinh(sqrt(2)*x) ). - G. C. Greubel, Jul 29 2017
Extensions
Edited and extended beyond a(5) by Klaus Brockhaus, Aug 06 2009
Comments