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A306934
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Coefficients of q-expansion of Eisenstein series G_{5/2}(tau) multiplied by 120.
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4
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1, -10, 0, 0, -70, -48, 0, 0, -120, -250, 0, 0, -240, -240, 0, 0, -550, -480, 0, 0, -528, -480, 0, 0, -720, -1210, 0, 0, -960, -720, 0, 0, -1080, -1440, 0, 0, -1750, -1200, 0, 0, -1680, -1920, 0, 0, -1680, -1488, 0, 0, -2160, -3370, 0, 0, -2640, -1680, 0, 0, -2400, -3360, 0, 0, -2880, -2640
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OFFSET
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0,2
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LINKS
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PROG
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(Sage)
def a(n):
if n==0: return 1
if (n%4) not in [0, 1]: return 0
D = Integer(n).squarefree_part()
f = Integer(sqrt(n/D))
if (D%4) not in [0, 1]: D, f = 4*D, f//2
X = kronecker_character(D)
s = sum([moebius(d)*X(d)*d*sigma(f/d, 3) for d in f.divisors()])
return round((120*X.lfunction(100)(-1)*s).real()) # Robin Visser, Feb 24 2024
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CROSSREFS
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KEYWORD
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sign
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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