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A132229 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. 3
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 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
REFERENCES
Computed by Sam Taylor.
LINKS
J. N. Cooper, D. Eichhorn and K. O'Bryant, Reciprocals of binary power series
FORMULA
The terms are the exponents in the expansion of 1/((1-x)S) read mod 2 where S = Sum_{s >= 0} x^{s^2}.
MATHEMATICA
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 *)
CROSSREFS
Cf. A108345.
Sequence in context: A105107 A002253 A032716 * A028750 A028787 A028796
KEYWORD
nonn
AUTHOR
Nadia Heninger, Dec 13 2007
STATUS
approved

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Last modified March 18 21:02 EDT 2024. Contains 370951 sequences. (Running on oeis4.)