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 A229062 1 if n is representable as sum of two nonnegative squares. 6
 1, 1, 1, 0, 1, 1, 0, 0, 1, 1, 1, 0, 0, 1, 0, 0, 1, 1, 1, 0, 1, 0, 0, 0, 0, 1, 1, 0, 0, 1, 0, 0, 1, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 0, 0, 1, 0, 0, 0, 1, 1, 0, 1, 1, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 1, 0, 0, 1, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 0, 1, 1, 0, 0, 1, 0, 1, 0, 0, 1, 0, 0, 0, 1 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Characteristic function of A001481. a(n) = 1 if A000161(n) > 0. a(A022544(n)) = 0. Multiplicative because A002654 is. - Andrew Howroyd, Aug 01 2018 LINKS MATHEMATICA Join[{1}, Table[If[SquaresR[2, n]>1, 1, 0], {n, 120}]] (* Harvey P. Dale, Aug 25 2017 *) PROG (PARI) a(n)=my(f=0); my(r=sqrtint(n)); forstep(i=r, 1, -1, if(issquare(n-i*i), f=1; break)); f a(n)={sumdiv( n, d, (d%4==1) - (d%4==3)) > 0} \\ Andrew Howroyd, Aug 01 2018 CROSSREFS Cf. A002654, A070176. Partial sums are in A102548. Sequence in context: A079559 A175480 A285568 * A014577 A157926 A263243 Adjacent sequences:  A229059 A229060 A229061 * A229063 A229064 A229065 KEYWORD nonn,mult AUTHOR Ralf Stephan, Sep 17 2013 STATUS approved

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Last modified October 16 23:50 EDT 2019. Contains 328103 sequences. (Running on oeis4.)