%I #10 Nov 09 2020 21:34:11
%S 1,2,5,12,26,13,4,52,21,28693,1128,2431,1221,16,71954,11,7,153888,8,
%T 27417323062119920,496,14,9,223378173194137397198,5760923,2403,149,
%U 134,10,452,47,406,71,19,27,20,37607875619,150886,22544062111497849
%N a(n) is the least number k such that 1/prime(k) has repeating decimal expansion of period n.
%H <a href="/index/1#1overn">Index entries for sequences related to decimal expansion of 1/n</a>
%F a(0) = 1; a(n) = A000720(A007138(n)).
%e 1/prime(1) = 1/2 = 0.5 (finite decimal expansion).
%e 1/prime(2) = 1/3 = 0.3(3)... (period 1).
%e 1/prime(5) = 1/11 = 0.09(09)... (period 2).
%e 1/prime(12) = 1/37 = 0.027(027)... (period 3).
%Y Cf. A000720, A002371, A003060, A007138.
%K nonn,base
%O 0,2
%A _Ilya Gutkovskiy_, Nov 09 2020
%E a(19)-a(38) from _Daniel Suteu_, Nov 09 2020 [using data from A007138 and A234317]