cp's OEIS Frontend

A002149 Largest prime p==3 (mod 8) such that Q(sqrt(-p)) has class number 2n+1.

%I A002149 M5407 N2350 #26 Aug 06 2022 07:17:56
%S A002149 163,907,2683,5923,10627,15667,20563,34483,37123,38707,61483,90787,
%T A002149 93307,103387,166147,133387,222643,210907,158923,253507,296587
%N A002149 Largest prime p==3 (mod 8) such that Q(sqrt(-p)) has class number 2n+1.
%C A002149 Most of these values are only conjectured to be correct.
%C A002149 Apr 15 2008: _David Broadhurst_ says: I computed class numbers for prime discriminants with |D| < 10^9, but stopped when the first case with |D| > 5*10^8 was observed. That factor of 2 seems to me to be a reasonable margin of error, when you look at the pattern of what is included.
%C A002149 Arno, Robinson, & Wheeler prove a(0)-a(11). - _Charles R Greathouse IV_, Apr 25 2013
%D A002149 N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
%D A002149 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H A002149 David Broadhurst, <a href="/A002149/b002149.txt">Table of n, a(n) for n = 0..739</a> (conjectural; see comment)
%H A002149 Steven Arno, M. L. Robinson, and Ferrell S. Wheeler, <a href="http://matwbn.icm.edu.pl/ksiazki/aa/aa83/aa8341.pdf">Imaginary quadratic fields with small odd class number</a>, Acta Arith. 83 (1998), pp. 295-330.
%H A002149 D. Shanks, <a href="https://doi.org/10.1090/S0025-5718-70-99853-4">Review of R. B. Lakein and S. Kuroda, Tables of class numbers h(-p) for fields Q(sqrt(-p)), p <= 465071</a>, Math. Comp., 24 (1970), 491-492.
%Y A002149 Cf. A002148, A003173, A006203.
%K A002149 nonn
%O A002149 0,1
%A A002149 _N. J. A. Sloane_
%E A002149 Edited by _Dean Hickerson_, Mar 17 2003