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 A033564 #29 Oct 20 2021 21:29:40 %S A033564 1,12,1213,12131214,1213121412131215,12131214121312151213121412131216, %T A033564 1213121412131215121312141213121612131214121312151213121412131217 %N A033564 a(n+1) = concatenation of a(n) and a(n)+1, with a(0)=1. %C A033564 The next term is too large to be included in the DATA section. - _N. J. A. Sloane_, Oct 20 2021 %t A033564 NestList[FromDigits[Join[IntegerDigits[#],IntegerDigits[#+1]]]&,1,6] (* _Jayanta Basu_, May 20 2013 *) %K A033564 nonn,base %O A033564 0,2 %A A033564 Wolfgang Scheufele (ws(AT)pi3.informatik.uni-mannheim.de)