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%I #12 Jun 08 2015 02:24:51
%S 3,4,7,13,25,34,37,97
%N Number n such that the n-th term of "concatenate next digit at right hand end (where the next digit after 9 is again 1)" is a semiprime.
%C First unknown: 361.
%e a(4) = 13 so 1234567891234 = 2 * 617283945617 is a semiprime.
%Y Cf. A057137.
%K nonn,base
%O 1,1
%A _Eric Chen_, Dec 26 2014
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