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 A351666 Discriminants of imaginary quadratic fields with class number 28 (negated). 7
 831, 935, 1095, 1311, 1335, 1364, 1455, 1479, 1496, 1623, 1703, 1711, 1855, 1976, 2024, 2055, 2120, 2127, 2324, 2359, 2431, 2455, 2564, 2607, 2616, 2703, 3224, 3272, 3396, 3419, 3487, 3535, 3572, 3576, 3608, 3624, 3731, 3848, 3995, 4040, 4183, 4279, 4344 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Sequence contains 457 terms; largest is 126043. The class groups associated to 174 of the above discriminants are isomorphic to C_28, and the remaining 283 have a class group isomorphic to C_14 X C_2. LINKS Andy Huchala, Table of n, a(n) for n = 1..457 Eric Weisstein's World of Mathematics, Class Number PROG (Sage) ls = [(QuadraticField(-n, 'a').discriminant(), QuadraticField(-n, 'a').class_number()) for n in (0..10000) if is_fundamental_discriminant(-n) and not is_square(n)]; [-a[0] for a in ls if a[1] == 28] (PARI) isok(n) = {isfundamental(-n) && quadclassunit(-n).no == 28}; \\ Michel Marcus, Mar 02 2022 CROSSREFS Cf. A006203, A013658, A014602, A014603, A046002-A046020, A046125, A056987, A351664. Sequence in context: A252423 A252416 A125519 * A045070 A186956 A252561 Adjacent sequences: A351663 A351664 A351665 * A351667 A351668 A351669 KEYWORD nonn,fini,full AUTHOR Andy Huchala, Feb 16 2022 STATUS approved

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Last modified March 30 09:39 EDT 2023. Contains 361609 sequences. (Running on oeis4.)