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Number of ordered set partitions of {1,2,...,n} such that no part has the same size as any of its four immediate predecessors.
2

%I #4 May 01 2016 10:46:42

%S 1,1,1,7,9,31,403,757,2873,12607,333051,761377,3699435,16383121,

%T 108710085,4855474267,28123899993,241045678351,2865769028107,

%U 22701288941281,238433702214659,4399193720759677,46157742163810905,514035796837721671,8889375296702138075

%N Number of ordered set partitions of {1,2,...,n} such that no part has the same size as any of its four immediate predecessors.

%H Alois P. Heinz, <a href="/A272432/b272432.txt">Table of n, a(n) for n = 0..80</a>

%Y Column k=4 of A261959.

%K nonn

%O 0,4

%A _Alois P. Heinz_, Apr 29 2016