OFFSET
0,2
COMMENTS
This is the sequence tesseq(X) with X = .5'i + .5i' + 'ii' - .5'jj' + 1.5'kk' - 1. See A108946.
LINKS
Robert Munafo, Sequences Related to Floretions
Index entries for linear recurrences with constant coefficients, signature (-4,0,4,1).
FORMULA
a(0)=-1, a(1)=4, a(2)=-13, a(3)=49, a(n)=-4*a(n-1)+4*a(n-3)+a(n-4). - Harvey P. Dale, Sep 06 2014
a(n) = (1 - (-1)^n + 2*cos(arccos(-2)*(n+1)))/4. - Eric Simon Jacob, Aug 17 2023
MATHEMATICA
CoefficientList[Series[-(1-3x^2-x^3)/(1+4x-4x^3-x^4), {x, 0, 40}], x] (* or *) LinearRecurrence[{-4, 0, 4, 1}, {-1, 4, -13, 49}, 40] (* Harvey P. Dale, Sep 06 2014 *)
CROSSREFS
KEYWORD
sign,easy
AUTHOR
N. J. A. Sloane, following a suggestion of Creighton Dement, Sep 06 2004
EXTENSIONS
Edited by Creighton Dement, Dec 11 2009
STATUS
approved