OFFSET
0,2
REFERENCES
P. Candelas et al., A pair of Calabi-yau manifolds as an exactly soluble superconformal theory, Nuclear Phys. B 359 (1991), 21-74 (see p. 73).
EXAMPLE
-1/5, -3/50, -11/375, -217/12500, -889/78125, -6207/781250, ...
MAPLE
a := proc(n) option remember; local t1; if n<0 then RETURN(0) elif n=0 then RETURN(-1/5) elif n=1 then RETURN(-3/50) else t1 := 125*n*(n-1)*(20*n^2-40*n+23)*a(n-1) -125*(n-1)*(30*n^3-150*n^2+261*n-157)*a(n-2) +(2500*n^4-22500*n^3+76625*n^2-116875*n+67226)*a(n-3) -625*(n-3)^4*a(n-4); t1 := eval(t1); RETURN(t1/( 625*n^2*(n^2-1) )); fi; end;
CROSSREFS
KEYWORD
sign,frac
AUTHOR
N. J. A. Sloane, Mar 30 2001
STATUS
approved