OFFSET
1,1
COMMENTS
Sequence contains 93 terms; largest is 103387.
The class group of Q[sqrt(-d)] is isomorphic to C_9 X C_3 for d = 3299, 19427, 34603, 89923, and 98443. For all other d in this sequence, the class group of Q[sqrt(-d)] is isomorphic to C_27.
LINKS
Andy Huchala, Table of n, a(n) for n = 1..93
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] == 27]
(PARI) isok(n) = {isfundamental(-n) && quadclassunit(-n).no == 27}; \\ Michel Marcus, Mar 02 2022
CROSSREFS
KEYWORD
nonn,fini,full
AUTHOR
Andy Huchala, Feb 16 2022
STATUS
approved