A102270 - OEIS

%I #13 Mar 14 2024 03:58:09

%S 16,8,8,8,16,8,16,16,16,8,16,32,8,8,8,8,32,8,16,64,32,8,32,8,8,128,32,

%T 32,32,16,8,8,8,16,16,8,8,8,128,16,8,8,16,32,8,16,32,8,8,8,128,8,8,8,

%U 16,8,64,8,8,8,16,8,16,16,16,8,8,16,32,16,8,8,8,64,32,64,16,64,8,16,32

%N 2-class number of Q(sqrt(-21p)) as p runs through primes in A102269.

%H H. Cohn and J. C. Lagarias, <a href="http://doi.org/10.1090/S0025-5718-1983-0717716-8">On the existence of fields governing the 2-invariants of the classgroup of Q(sqrt{dp}) as p varies</a>, Math. Comp. 41 (1983), 711-730.

%o (Sage) [2^QuadraticField(-21*p).class_number().valuation(2) for p in Primes()[:1000] if (p%84) in [43, 67, 79]] # _Robin Visser_, Mar 13 2024

%Y Cf. A102269, A102271, A102272, A102273, A102274, A102275.

%K nonn

%O 1,1

%A _N. J. A. Sloane_, Feb 19 2005

%E More terms from _Robin Visser_, Mar 13 2024