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A033198 Discriminants of real quadratic number fields. 0
8, 12, 5, 24, 28, 40, 44, 13, 56, 60, 17, 76, 21, 88, 92, 104, 29, 120, 124, 33, 136, 140, 37, 152, 156, 41, 168, 172, 184, 188, 204, 53, 220, 57, 232, 236, 61, 248, 65, 264, 268, 69, 280, 284, 73, 296, 77, 312, 316, 328, 332, 85, 344, 348, 89, 364, 93, 376, 380, 97 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

REFERENCES

David A. Cox, "Primes of the Form x^2 + n y^2", Wiley, 1989, p. 103.

LINKS

Table of n, a(n) for n=1..60.

FORMULA

For squarefree n >= 2, list n if n=1 mod 4 else 4n.

MAPLE

with(numtheory): a:= proc(n) if issqrfree(n) then RETURN(piecewise(n mod 4=1, n, 4*n)) else RETURN(NULL) fi: end: seq(a(n), n=2..150); # C. Ronaldo (aga_new_ac(AT)hotmail.com), Jan 03 2005

CROSSREFS

Sequence in context: A004473 A114404 A173457 * A072900 A203836 A220665

Adjacent sequences:  A033195 A033196 A033197 * A033199 A033200 A033201

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane

EXTENSIONS

More terms from C. Ronaldo (aga_new_ac(AT)hotmail.com), Jan 03 2005

STATUS

approved

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Last modified January 18 17:18 EST 2022. Contains 350455 sequences. (Running on oeis4.)