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2, 2, 2, 1, 2, 2, 2, 1, 1, 2, 2, 8, 2, 6, 16, 1, 2, 3, 2, 2, 4, 2, 2, 4, 1, 6, 2, 4, 2, 16, 2, 1, 4, 2, 24, 1, 2, 6, 16, 2, 2, 12, 2, 8, 6, 2, 2, 4, 3, 1, 8, 2, 2, 6, 16, 48, 4, 2, 2, 8, 2, 6, 4, 1, 12, 4, 2, 2, 4, 24, 2, 3, 2, 6, 4, 8, 12, 48, 2, 2, 1, 2, 2, 8, 4, 6, 16, 20, 2, 6, 8, 4, 4, 2, 48, 4, 2, 3
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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EXAMPLE
| If a(n)=1, then n is either square or twice a square.
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MATHEMATICA
| sep[n_]:=Module[{s=DivisorSigma[1, n], e=EulerPhi[n]}, GCD[s+e, s-e]]; Array[sep, 100] (* From Harvey P. Dale, June 17 2011 *)
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CROSSREFS
| Cf. A000203, A000010, A051612, A065387.
Sequence in context: A067597 A139394 A125829 * A160385 A076881 A136754
Adjacent sequences: A077096 A077097 A077098 * A077100 A077101 A077102
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KEYWORD
| nonn
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AUTHOR
| Labos E. (labos(AT)ana.sote.hu), Nov 06 2002
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EXTENSIONS
| Edited by Dean Hickerson (dean.hickerson(AT)yahoo.com), Nov 07 2002
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