| # get th2, th3, th4 = Jacobi theta constants out to degree maxd
maxd:=2001:
temp0:=trunc(evalf(sqrt(maxd)))+2: a:=0: for i from -temp0 to temp0 do a:=a+q^( (i+1/2)^2): od: th2:=series(a, q, maxd):
a:=0: for i from -temp0 to temp0 do a:=a+q^(i^2): od: th3:=series(a, q, maxd):
th4:=series(subs(q=-q, th3), q, maxd):
# get Leech etc
t1:=th2^8+th3^8+th4^8: e8:=series(t1/2, q, maxd):
t1:=th2^8*th3^8*th4^8: delta24:=series(t1/256, q, maxd):
leech:=series(e8^3-720*delta24, q, maxd):
u1:=series(leech^3, q, maxd):
#u2:=series(leech^2*delta24, q, maxd):
u3:=series(leech*delta24^2, q, maxd):
u4:=series(delta24^3, q, maxd):
u5:=series(u1-589680*u3-78624000*u4, q, maxd);
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