%I #29 Oct 20 2021 21:29:40
%S 1,12,1213,12131214,1213121412131215,12131214121312151213121412131216,
%T 1213121412131215121312141213121612131214121312151213121412131217
%N a(n+1) = concatenation of a(n) and a(n)+1, with a(0)=1.
%C The next term is too large to be included in the DATA section. - _N. J. A. Sloane_, Oct 20 2021
%t NestList[FromDigits[Join[IntegerDigits[#],IntegerDigits[#+1]]]&,1,6] (* _Jayanta Basu_, May 20 2013 *)
%K nonn,base
%O 0,2
%A Wolfgang Scheufele (ws(AT)pi3.informatik.uni-mannheim.de)