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A175361
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Partial sums of A000141.
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10
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1, 13, 73, 233, 485, 797, 1341, 2301, 3321, 4197, 5757, 8157, 10237, 12277, 15541, 19701, 23793, 27273, 31653, 38853, 45405, 50013, 58173, 68733, 76957, 84769, 94969, 108089, 120569, 130673, 144817, 164017, 180397, 191917, 209317, 234277, 252673, 269113, 293593
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OFFSET
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0,2
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COMMENTS
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LINKS
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FORMULA
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MATHEMATICA
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CoefficientList[Series[EllipticTheta[3, x]^6/(1-x), {x, 0, 35}], x] (* Stefano Spezia, Jun 21 2024 *)
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PROG
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(Python)
from math import prod
from sympy import factorint
c = 1
for m in range(1, n+1):
f = [(p, e, (0, 1, 0, -1)[p&3]) for p, e in factorint(m).items()]
c += (prod((p**(e+1<<1)-a)//(p**2-a) for p, e, a in f)<<2)-prod(((k:=p**2*a)**(e+1)-1)//(k-1) for p, e, a in f)<<2
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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