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 A104430 #18 Feb 07 2022 15:49:52
%S A104430 1,1,2,4,11,23,68,161,488,1249,3771,10388,35725,110449,387057,1411784,
%T A104430 5938390,26054261,129231034,708657991
%N A104430 Number of ways to split 1, 2, 3, ..., 4n into n arithmetic progressions each with 4 terms.
%H A104430 Rémy Sigrist, <a href="/A104430/a104430.txt">C program</a>
%e A104430 {{{1,2,3,4},{5,6,7,8},{9,10,11,12}}, {{1,2,3,4},{5,7,9,11},{6,8,10,12}}, {{1,3,5,7},{2,4,6,8},{9,10,11,12}}, {{1,4,7,10},{2,5,8,11},{3,6,9,12}}} are the 4 ways to split 1, 2, 3, ..., 12 into 3 arithmetic progressions each with 4 terms. Thus a(3)=4.
%o A104430 (C) See Links section.
%Y A104430 Cf. A104429, A104431-A104443, A337520.
%K A104430 nonn,more
%O A104430 0,3
%A A104430 _Jonas Wallgren_, Mar 17 2005
%E A104430 a(11)-a(17) from _Alois P. Heinz_, Dec 28 2011
%E A104430 a(0)=1 prepended by _Alois P. Heinz_, Nov 18 2020
%E A104430 a(18)-a(19) from _Rémy Sigrist_, Feb 07 2022