This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A213974 #14 Aug 02 2017 12:01:25
%S A213974 22,33,222,333,2222,2323,3232,3333,22222,33333,222222,223223,232232,
%T A213974 232323,233233,322322,323232,323323,332332,333333,2222222,3333333,
%U A213974 22222222,22232223,22322232,22332233,23222322,23232323,23322332,23332333,32223222,32233223,32323232,32333233,33223322,33233323,33323332,33333333
%N A213974 List of imprimitive words over the alphabet {2,3}.
%C A213974 A word w is primitive if it cannot be written as u^k with k>1; otherwise it is imprimitive.
%C A213974 The {0,1} version of this sequence is 00, 11, 000, 111, 0000, 0101, 1010, 1111, 00000, 11111, 000000, 001001, 010010, 010101, 011011, 100100, 101010, 101101, 110110, 111111 but this cannot be included as a sequence in the OEIS since it contains nonzero "numbers" beginning with 0.
%C A213974 This sequence results from A213973 by replacing each digit 1 by 2, and from A213972 by replacing all digits 2 by 3 and all digits 1 by 2. - _M. F. Hasler_, Mar 10 2014
%D A213974 A. de Luca and S. Varricchio, Finiteness and Regularity in Semigroups and Formal Languages, Monographs in Theoretical Computer Science, Springer-Verlag, Berlin, 1999. See p. 10.
%F A213974 Equals A032810 intersect A239018. - _M. F. Hasler_, Mar 10 2014
%o A213974 (PARI) for(n=1, 8, p=vector(n, i, 10^(n-i))~; forvec(d=vector(n, i, [2, 3]), is_A239017(m=d*p)||print1(m", "))) \\ _M. F. Hasler_, Mar 10 2014
%Y A213974 Cf. A213969, A213970, A213971, A213972, A213973.
%K A213974 nonn
%O A213974 1,1
%A A213974 _N. J. A. Sloane_, Jun 30 2012
%E A213974 More terms from _M. F. Hasler_, Mar 10 2014