OFFSET
0,4
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (-4,-4).
FORMULA
a(n+2) = (-1)^(n+1) * A001792(n).
From R. J. Mathar, Nov 23 2009: (Start)
a(n) = -4*a(n-1) -4*a(n-2) = (-2)^(n-3)*n, n>3.
G.f.: x*(1 + 3*x + 3*x^2)/(1 + 2*x)^2. (End)
MATHEMATICA
Join[{0, 1, -1, 3}, LinearRecurrence[{-4, -4}, {-8, 20}, 50]] (* G. C. Greubel, Jul 14 2016 *)
CoefficientList[Series[x (1 + 3 x + 3 x^2) / (1 + 2 x)^2, {x, 0, 33}], x] (* Vincenzo Librandi, Jul 15 2016 *)
PROG
(PARI) a(n)=(-2)^if(n>1, n-3)*n \\ M. F. Hasler, Jan 25 2012
(Magma) [0, 1] cat [(-2)^(n-3)*n: n in [2..35]]; // Vincenzo Librandi, Jul 15 2016
CROSSREFS
KEYWORD
sign,easy
AUTHOR
Paul Curtz, Nov 19 2009
EXTENSIONS
Comments turned into formulas, out-of-scope material moved to A026741 by R. J. Mathar, Nov 23 2009
STATUS
approved