OFFSET
0,1
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (2,1,-2).
FORMULA
a(n) = 2*a(n-1) + a(n-2) - 2*a(n-3), n >= 3.
a(n+1) - a(n) = A048573(n-1).
a(n) - a(n-2) = 5*2^n.
a(n+1) - 2*a(n) = ((-1)^n-1)/2 = -A000035(n).
G.f.: ( 2-3*x^2 ) / ( (x-1)*(2*x-1)*(1+x) ). - R. J. Mathar, Jul 07 2011
a(n) = ceiling( (5/3)*(2^n) ). - Wesley Ivan Hurt, Jun 28 2013
MATHEMATICA
LinearRecurrence[{2, 1, -2}, {2, 4, 7}, 40] (* Harvey P. Dale, Feb 11 2015 *)
PROG
(PARI) a(n)=(10<<n+3)\/6 \\ Charles R Greathouse IV, Jul 07 2011
(Magma) [( 10*2^n+3-(-1)^n )/6: n in [0..40]]; // Vincenzo Librandi, Aug 05 2011
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Paul Curtz, Dec 05 2009
EXTENSIONS
Definition replaced by the Lava formula of 2009. Contents converted to formulas. - R. J. Mathar, Jul 07 2011
STATUS
approved