OFFSET
1,2
COMMENTS
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..1000
Index entries for linear recurrences with constant coefficients, signature (0, 2).
FORMULA
a(n) = (5 + 3*(-1)^n)*2^((2*n -5 +(-1)^n)/4).
G.f.: x*(1+8*x)/(1-2*x^2).
E.g.f.: 4*cosh(sqrt(2)*x) + (1/sqrt(2))*sinh(sqrt(2)*x) - 4. - G. C. Greubel, Aug 12 2017
MATHEMATICA
CoefficientList[Series[(1 - x)/(1 - 10*x + 17*x^2), {x, 0, 50}], x] (* G. C. Greubel, Aug 12 2017 *)
PROG
(Magma) [ n le 2 select 7*n-6 else 2*Self(n-2): n in [1..41] ];
(PARI) x='x+O('x^50); Vec(x*(1+8*x)/(1-2*x^2)) \\ G. C. Greubel, Aug 12 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
Klaus Brockhaus, Aug 17 2009
STATUS
approved