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A053866
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Parity of sum of divisors of n.
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6
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0, 1, 1, 0, 1, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,1
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LINKS
| Michael Gilleland, Some Self-Similar Integer Sequences
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FORMULA
| a(n) = A000203(n) mod 2. a(n)=1 iff n>0 is a square or twice a square.
Multiplicative with a(2^e)=1, a(p^e)=1 if e even, 0 otherwise.
a(n) = A093709(n) if n>0.
Dirichlet g.f.: zeta(2s)(1+2^-s). - Michael Somos Apr 12 2004
a(n) = A001157(n) mod 2. - R. J. Mathar, Apr 02 2011
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MAPLE
| A053866:= (n -> numtheory[sigma](n) mod 2):
seq (A053866(n), n=0..104); # - Jani Melik, Jan 28 2011
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PROG
| (PARI) a(n)=if(n<1, 0, issquare(n)|issquare(2*n)) /* Michael Somos Apr 12 2004 */
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CROSSREFS
| Cf. A000203, A028982.
Sequence in context: A079336 A057215 A029691 * A156595 A143222 A010060
Adjacent sequences: A053863 A053864 A053865 * A053867 A053868 A053869
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KEYWORD
| nonn,mult
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AUTHOR
| Henry Bottomley (se16(AT)btinternet.com), Mar 29 2000
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EXTENSIONS
| More terms from James A. Sellers (sellersj(AT)math.psu.edu), Apr 08 2000
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