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