OFFSET
0,3
COMMENTS
Row sums of Riordan array (1-x-2x^2,x(1-x)), A109246.
After the initial terms, cyclic with period 8: [0,0,-3,-3,0,0,3,3]. - Antti Karttunen, Aug 12 2017
LINKS
Antti Karttunen, Table of n, a(n) for n = 0..8191
Index entries for linear recurrences with constant coefficients, signature (0,0,0,-1).
FORMULA
a(0)=1, a(1)=0, a(2)=-3, a(3)=-3, a(4)=0, a(n)=-a(n-4) - Harvey P. Dale, Mar 24 2012
For n > 0, a(n) = -3 * A132380(n). - Antti Karttunen, Aug 12 2017
MATHEMATICA
CoefficientList[Series[(1-3x^2-3x^3+x^4)/(1+x^4), {x, 0, 90}], x] (* or *) Join[{1}, LinearRecurrence[{0, 0, 0, -1}, {0, -3, -3, 0}, 90]] (* Harvey P. Dale, Mar 24 2012 *)
PROG
(Scheme) (define (A109247 n) (case n ((0) 1) ((1 4) 0) ((2 3) -3) (else (- (A109247 (- n 4)))))) ;; (After Harvey P. Dale's Mar 24 2012 recurrence) - Antti Karttunen, Aug 12 2017
(PARI) Vec((1-3*x^2-3*x^3+x^4)/(1+x^4) + O(x^80)) \\ Jinyuan Wang, Mar 22 2020
CROSSREFS
KEYWORD
sign,easy
AUTHOR
Paul Barry, Jun 23 2005
STATUS
approved