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A151758

G.f.: Theta^2-Theta, where Theta = Sum_{k>=0} x^(2^k).

0, -1, 0, 2, 0, 2, 2, 0, 0, 2, 2, 0, 2, 0, 0, 0, 0, 2, 2, 0, 2, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 2, 2, 0, 2, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 2, 0, 2, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0

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OFFSET

0,4

COMMENTS

If we omit the "-x" term and divide by 2, we get the characteristic function of the numbers with binary weight 2 (A018900, A151774).

LINKS

Table of n, a(n) for n=0..104.

MATHEMATICA

w[n_] := IntegerDigits[n, 2] // Total;

a[n_] := If[n == 1, -1, 2 Boole[w[n] == 2]];

a /@ Range[0, 104] (* Jean-François Alcover, Mar 31 2021 *)

CROSSREFS