OFFSET
0,8
COMMENTS
G.f. y=Sum_{k>0} f(n)x^n satisfies y''+y/(1+x)=0. - Michael Somos, Feb 14 2004
REFERENCES
H. K. Wilson, Ordinary Differential Equations, Addison-Wesley, 1971, p. 154.
EXAMPLE
Sequence f(n) begins 0, 1, 0, -1/6, 1/12, -1/24, 1/40, -17/1008, 41/3360, ...
PROG
(PARI) a(n)=local(y); if(n<0, 0, y=O(x); for(k=1, n, y=x+intformal(intformal(-y/(1+x)))); numerator(polcoeff(y, n)))
CROSSREFS
KEYWORD
sign,frac
AUTHOR
N. J. A. Sloane, Feb 08 2004
STATUS
approved