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A092205
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Number of units in the imaginary quadratic field Q[Sqrt[ -n]].
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4
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4, 2, 6, 4, 2, 2, 2, 2, 4, 2, 2, 6, 2, 2, 2, 4, 2, 2, 2, 2, 2, 2, 2, 2, 4, 2, 6, 2, 2, 2, 2, 2, 2, 2, 2, 4, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 6, 4, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 4, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 6, 2, 2, 2, 2, 2, 4, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 4, 2, 2, 2, 2, 2
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| Sequence of n such that a(n)=2 gives A092206; a(n)=4 gives A000290; a(n)=6 gives A033428. - Marc LeBrun (mlb(AT)well.com), Apr 12 2006
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LINKS
| Nathaniel Johnston, Table of n, a(n) for n = 1..10000
Eric Weisstein's World of Mathematics, Unit
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EXAMPLE
| For n=1, the units are +/-1, +/-i.
For n=2, the units are +/-1, +/-w, +/-w^2, where w is a cube root of unity.
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MAPLE
| A092205 := proc(n) if(type(sqrt(n), integer))then return 4: elif(n mod 3 = 0 and type(sqrt(n/3), integer))then return 6: else return 2: fi: end: seq(A092205(n), n=1..105); # Nathaniel Johnston, Jun 26 2011
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CROSSREFS
| Cf. A092206, A000290, A033482.
Sequence in context: A097467 A169839 A187109 * A059853 A136527 A138614
Adjacent sequences: A092202 A092203 A092204 * A092206 A092207 A092208
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KEYWORD
| nonn,easy
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AUTHOR
| Eric Weisstein (eric(AT)weisstein.com), Feb 24, 2004
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