OFFSET
1,1
LINKS
Index entries for linear recurrences with constant coefficients, signature (0,0,0,-1).
FORMULA
Period 8 sequence: [ -1,-1,0,-1,1,1,0,1].
G.f.: -x*(1+x+x^3)/(1+x^4). [corrected by R. J. Mathar, Jul 22 2009]
a(n) = -a(n-4). - R. J. Mathar, Jul 22 2009
EXAMPLE
at k = 4*n: 1/(2*A080277(n));
at k = 4*n+1: 1/(2*A080277(n)-1);
at k = 4*n+2: 1/(2*A080277(n)-2);
at k = 4*n-1: 0.
Convergents begin:
-1/1, -1/2, 0/-1, -1/-2, 1/1, 1/0, 0/1, 1/8,
-1/-7, -1/-6, 0/-1, -1/-10, 1/9, 1/8, 0/1, 1/24,
-1/-23, -1/-22, 0/-1, -1/-26, 1/25, 1/24, 0/1, 1/32,
-1/-31, -1/-30, 0/-1, -1/-34, 1/33, 1/32, 0/1, 1/64, ...
PROG
(PARI) {a(n)=local(p=-1, q=+2, v=vector(n, i, if(i%2==1, p, q*2^valuation(i/2, 2)))); contfracpnqn(v)[1, 1]}
CROSSREFS
KEYWORD
frac,sign
AUTHOR
Paul D. Hanna, May 01 2006
STATUS
approved