OFFSET
0,2
COMMENTS
A floretion-generated sequence: 'i + 0.5('ij' + 'ik' + 'ji' + 'jk' + 'ki' + 'kj').
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..1000
Creighton Dement, Online Floretion Multiplier [broken link].
Index entries for linear recurrences with constant coefficients, signature (0,1,2).
FORMULA
a(1)=1, a(2)=-2, a(3)=2, a(n) = 1*a(n-2) + 2*a(n-3) for n >= 3. - Harvey P. Dale, Apr 24 2011
MATHEMATICA
CoefficientList[Series[(x-1)^2/(1-x^2-2*x^3), {x, 0, 40}], x] (* or *) LinearRecurrence[{0, 1, 2}, {1, -2, 2}, 40] (* Harvey P. Dale, Apr 24 2011 *)
PROG
(PARI) a(n)=([0, 1, 0; 0, 0, 1; 2, 1, 0]^n*[1; -2; 2])[1, 1] \\ Charles R Greathouse IV, Oct 03 2016
(Magma) I:=[1, -2, 2]; [n le 3 select I[n] else Self(n-2) + 2*Self(n-3): n in [1..30]]; // G. C. Greubel, Jun 27 2018
CROSSREFS
KEYWORD
easy,sign
AUTHOR
Creighton Dement, Apr 08 2009
STATUS
approved