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 A094612 Fundamental discriminants of real quadratic number fields with class number 3. 14
 229, 257, 316, 321, 469, 473, 568, 733, 761, 892, 993, 1016, 1101, 1229, 1257, 1304, 1373, 1436, 1489, 1509, 1772, 1901, 1929, 1957, 2021, 2089, 2101, 2177, 2213, 2429, 2557, 2589, 2636, 2677, 2713, 2777, 2857, 2917, 2981, 3173, 3221, 3229, 3261, 3356, 3569 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS G. C. Greubel, Table of n, a(n) for n = 1..1000 Eric Weisstein's World of Mathematics, Class Number MATHEMATICA Select[Range[3569], NumberFieldDiscriminant@Sqrt[#] == # && NumberFieldClassNumber@Sqrt[#] == 3 &] (* Arkadiusz Wesolowski, Oct 22 2012 *) PROG (PARI) {ok(n) = n>10 && isfundamental(n) && qfbclassno(n)==3}; for(n=1, 3600, if(ok(n)==1, print1(n, ", "))) \\ G. C. Greubel, Mar 01 2019 (Sage) is_fund_and_qfbcn_1 = lambda n: is_fundamental_discriminant(n) and QuadraticField(n, 'a').class_number() == 3; A094612 = lambda n: filter(is_fund_and_qfbcn_1, (1, 2, .., n)); A094612(3700) # G. C. Greubel, Mar 01 2019 CROSSREFS Cf. A003656, A094619, A094613-A094614, A218156-A218160. Sequence in context: A062589 A250235 A250236 * A250237 A112847 A157348 Adjacent sequences:  A094609 A094610 A094611 * A094613 A094614 A094615 KEYWORD nonn AUTHOR Eric W. Weisstein, May 14 2004 EXTENSIONS Edited by N. J. A. Sloane, May 01 2010 STATUS approved

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Last modified January 27 22:40 EST 2021. Contains 340489 sequences. (Running on oeis4.)