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A035115 Relative class number h- of cyclotomic field Q(zeta_m) where m is n-th term of A035113.

%I A035115 #18 Mar 04 2020 22:53:15
%S A035115 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,3,1,2,1,3,2,3,
%T A035115 1,8,9,5,17,8,5,9,4,37,9,7,19,19,121,10,11,55,55,11,211,43,69,201,695,
%U A035115 64,351,13,468,39,507,156,84,75,4889,2593,1536,10752,41241,76301,1280,6795
%N A035115 Relative class number h- of cyclotomic field Q(zeta_m) where m is n-th term of A035113.
%D A035115 L. C. Washington, Introduction to Cyclotomic Fields, Springer, p. 353.
%F A035115 a(n) = A061653(A035113(n)).
%t A035115 (* This is only a recomputation of the existing data. *)
%t A035115 terms = 76;
%t A035115 A035113 = Sort[Select[Range[3 terms], Mod[#, 4] != 2&], EulerPhi[#1] <= EulerPhi[#2]&];
%t A035115 A061653 = Import["https://oeis.org/A061653/b061653.txt", "Table"][[All, 2]];
%t A035115 a[n_] := A061653[[A035113[[n]] ]];
%t A035115 Array[a, terms] (* _Jean-François Alcover_, Aug 17 2019 *)
%Y A035115 Cf. A000010, A035113, A035114, A055513, A061494, A061653.
%K A035115 nonn,nice
%O A035115 1,28
%A A035115 _N. J. A. Sloane_
%E A035115 Changed 41421 to 41241, value is given incorrectly in first edition of Washington, _Matthew Johnson_, Jul 20 2013