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A060346 Numerators of sequence arising from study of Calabi-Yau manifolds. 1

%I

%S -1,-3,-11,-217,-889,-6207,-395583,-11872529,-51190172,-3320575453,

%T -71855148782,-1138862383991,-73603597626136,-585764974480039,

%U -5810293262069806,-9158417736096173491,-75787432383189077231,-289633090947850663933

%N Numerators of sequence arising from study of Calabi-Yau manifolds.

%D 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).

%e -1/5, -3/50, -11/375, -217/12500, -889/78125, -6207/781250, ...

%p 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)*f(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;

%Y Cf. A060347.

%K sign,frac

%O 0,2

%A _N. J. A. Sloane_, Mar 30 2001

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Last modified June 28 19:10 EDT 2022. Contains 354907 sequences. (Running on oeis4.)