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A132229
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The set N such that each positive integer can be written in the form s^2 + n, s>=0, n in N, in an odd number of ways.
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3
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2, 5, 6, 8, 13, 14, 15, 16, 18, 19, 20, 21, 22, 27, 28, 31, 35, 36, 39, 40, 45, 46, 49, 53, 54, 59, 60, 63, 64, 65, 66, 67, 68, 69, 70, 72, 79, 80, 83, 84, 85, 86, 89, 90, 97, 101, 102, 107, 108, 113, 114, 117, 118, 119, 120, 127, 137, 138, 149, 150, 153
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OFFSET
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1,1
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REFERENCES
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Computed by Sam Taylor.
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LINKS
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FORMULA
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The terms are the exponents in the expansion of 1/((1-x)S) read mod 2 where S = Sum_{s >= 0} x^{s^2}.
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MATHEMATICA
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m = maxExponent = 13;
S = Sum[x^(s^2), {s, 0, m}];
(Exponent[#, x]& /@ (List @@ (Normal[1/((1-x)S) + O[x]^(m^2)] /. c_ x^p_ :> Mod[c, 2] x^p))) // Rest (* Jean-François Alcover, Dec 10 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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