cp's OEIS Frontend

A061494 Relative class number h- of cyclotomic field Q(zeta_n) where n runs through positive integers not congruent to 2 (mod 4) [A042965, but omitting the initial 0].

%I A061494 #17 Mar 13 2015 00:21:52
%S A061494 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,3,1,1,1,1,8,9,1,1,1,1,37,2,1,121,211,
%T A061494 1,1,695,1,43,5,3,4889,10,2,9,41241,1,76301,7,17,64,853513,8,69,
%U A061494 3882809,3,11957417,11,19,1280,100146415,5,2593,838216959,1,6205,1536,55,13379363737,53872
%N A061494 Relative class number h- of cyclotomic field Q(zeta_n) where n runs through positive integers not congruent to 2 (mod 4) [A042965, but omitting the initial 0].
%C A061494 First edition of Washington incorrectly gives a(44) = h-(Q(zeta_59)) = 41421. [_Matthew Johnson_, Jul 20 2013]
%D A061494 L. C. Washington, Introduction to Cyclotomic Fields, Springer, pp. 353-360.
%F A061494 a(n) = A061653(A042965(n+1)). - _M. F. Hasler_, Feb 04 2009
%e A061494 n=17: the 17th number not == 2 mod 4 is 23, and Q(zeta_23) = 3 is the first time that h- is bigger than 1, so a(17) = 3.
%Y A061494 Cf. A035115, A055513, A061653, A042965.
%K A061494 nonn,nice
%O A061494 1,17
%A A061494 _N. J. A. Sloane_, Jun 16 2001
%E A061494 Missing term a(1) = 1 inserted by _N. J. A. Sloane_, Feb 05 2009 at the suggestion of _Tanya Khovanova_ and _M. F. Hasler_
%E A061494 More terms (from b-file of A061653), _Joerg Arndt_, Oct 07 2012
%E A061494 a(44) corrected by _Matthew Johnson_, Jul 20 2013