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A175372
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Number of integer pairs (x,y) satisfying x^4 + y^4 = n.
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2
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1, 4, 4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 8, 0, 0, 0, 0, 0, 0, 0
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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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G.f.: (1 + 2*Sum_{j>=1} x^(j^4))^2.
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MAPLE
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seq(coeff(series((1+2*add(x^(j^4), j=1..n))^2, x, n+1), x, n), n = 0 .. 120); # Muniru A Asiru, Oct 07 2018
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MATHEMATICA
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CoefficientList[Series[(1 + 2*Sum[x^(j^4), {j, 1, 100}])^2, {x, 0, 120}], x] (* G. C. Greubel, Oct 06 2018 *)
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PROG
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(PARI) x='x+O('x^120); Vec((1+2*sum(j=1, 50, x^(j^4)))^2) \\ G. C. Greubel, Oct 06 2018
(Magma) m:=120; R<x>:=PowerSeriesRing(Integers(), m); Coefficients(R!((1+2*(&+[x^(j^4): j in [1..50]]))^2)); // G. C. Greubel, Oct 06 2018
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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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