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 A287253 #6 May 22 2017 11:48:16 %S A287253 1,1,2,5,15,51,191,780,3440,16249,81736,435796,2453100,14529728, %T A287253 90294625,587256087,3988153356,28223370977,207745253237,1587804229045, %U A287253 12581186077773,103197641796678,875085283793768,7661468372063681,69173450911547978,643354845906697516 %N A287253 Number of set partitions of [n] such that all absolute differences between least elements of consecutive blocks are <= three. %H A287253 Alois P. Heinz, <a href="/A287253/b287253.txt">Table of n, a(n) for n = 0..586</a> %H A287253 Wikipedia, <a href="https://en.wikipedia.org/wiki/Partition_of_a_set">Partition of a set</a> %F A287253 a(n) = A287216(n,3). %F A287253 a(n) = A000110(n) for n <= 4. %Y A287253 Column k=3 of A287216. %Y A287253 Cf. A000110. %K A287253 nonn %O A287253 0,3 %A A287253 _Alois P. Heinz_, May 22 2017