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
KEYWORD
nonn,fini,full
AUTHOR
Andy Huchala, Feb 16 2022
STATUS
approved