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 A061892 #30 May 29 2021 10:16:19 %S A061892 0,3,1,3,3,6,10,28,108,1011,32511,9314238,84560776390, %T A061892 219625370880235960 %N A061892 Lionel-Levine-sequence generated by (1,0,0). %C A061892 A011784 allows the addition of a(-1)=0 and a(0)=2 using row A012257(-2)=1 and A012257(-1)=0 resp. row A012257(0)=2. In this sense A011784 / A012257 are "generated" by (1,0), A061892 / A061893 by (1,0,0), A061894 / A061895 by (2,0). %e A061892 a(4) = 3: (1,0,0), (3), (1,1,1), (1,2,3), (1,1,1,2,2,3). %o A061892 (Rexx) /* replace 1 0 0 with 1 0 to get A011784 */ %o A061892 S = ''; A = 1 0 0; do N = 1 to 10; T = words( A ); %o A061892 S = S word( A, T ); B = A; A = ''; do K = 1 to T; %o A061892 A = A space( copies( K '', word( B, T + 1 - K ))); %o A061892 end K; end N; T = words( A ); say S word( A, T ) T; %Y A061892 Cf. A011784, A012257, A061893, A061894. %K A061892 nonn,more %O A061892 0,2 %A A061892 _Frank Ellermann_, May 13 2001 %E A061892 a(11) from _Naohiro Nomoto_, May 10 2002 %E A061892 a(12) from _Michael Anthony Keyes_, Apr 14 2021 %E A061892 a(13) from _Michael Anthony Keyes_, May 13 2021