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 A239551 #6 May 01 2014 09:05:57
%S A239551 1,1,1,2,3,4,6,9,13,18,24,34,49,71,100,145,205,295,423,610,872,1260,
%T A239551 1804,2599,3733,5381,7725,11131,15996,23042,33133,47714,68608,98793,
%U A239551 142101,204585,294318,423683,609565,877457,1262508,1817205,2614832,3763553,5415668
%N A239551 Number of compositions of n such that the first part is 1 and the second differences of the parts are in {-1,0,1}.
%H A239551 Alois P. Heinz, <a href="/A239551/b239551.txt">Table of n, a(n) for n = 0..1000</a>
%F A239551 a(n) ~ c * d^n, where d=1.4391340589699362028978918824612984596732704665024595117321768607966..., c=0.5987103268327131789103863373328359387911710658212178254615152936898... - _Vaclav Kotesovec_, May 01 2014
%e A239551 a(6) = 6: [1,1,1,1,1,1], [1,1,1,1,2], [1,1,2,2], [1,2,2,1], [1,2,3], [1,5].
%Y A239551 Column k=1 of A239550.
%K A239551 nonn
%O A239551 0,4
%A A239551 _Alois P. Heinz_, Mar 21 2014