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 A053052 #8 Nov 16 2021 18:48:08 %S A053052 1,21,123,4321,12345,654321,1234567,87654321,123456789,10987654321, %T A053052 1234567891011,121110987654321,12345678910111213,1413121110987654321, %U A053052 123456789101112131415 %N A053052 Append n to the previous term, reverse alternate terms. %D A053052 Felice Russo, A set of new Smarandache functions, sequences and conjectures in number theory, American Research Press 2000 %Y A053052 Cf. A000422, A007908. %K A053052 easy,base,nonn %O A053052 1,2 %A A053052 _Felice Russo_, Feb 25 2000