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Search: id:A033197
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| A033197 |
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Discriminants of quadratic number fields Q(sqrt -n) for n square-free. |
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+0
3
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| -4, -8, -3, -20, -24, -7, -40, -11, -52, -56, -15, -68, -19, -84, -88, -23, -104, -116, -120, -31, -132, -136, -35, -148, -152, -39, -164, -168, -43, -184, -47, -51, -212, -55, -228, -232, -59, -244, -248, -260, -264, -67, -276, -280, -71, -292, -296, -308, -312, -79, -328, -83, -340, -344, -87, -356
(list; graph; listen)
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OFFSET
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1,1
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REFERENCES
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D. Cox, "Primes of Form x^2 + n y^2", Wiley, 1989, p. 103.
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LINKS
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T. D. Noe, Table of n, a(n) for n=1..10000
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FORMULA
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For n square-free and negative, a(n)=n if n=1 mod 4 else 4n.
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PROGRAM
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(PARI) bnd = 1000; L = vector(bnd); j = 1; for (i=1, bnd, if(issquarefree(i), L[j]=i:j=j+1)); M = vector(j-1); for (i=1, j-1, M[i]=if((L[i]%4==3), -L[i], -4*L[i])); M
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CROSSREFS
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Values of n run through A005117. See A000924 for class numbers of these fields.
Sequence in context: A021678 A066199 A103647 this_sequence A124002 A014457 A092511
Adjacent sequences: A033194 A033195 A033196 this_sequence A033198 A033199 A033200
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KEYWORD
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sign,easy,nice
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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