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A226438 Number of permutations of {1..n} with fewer than 5 interior elements having values lying between the values of their neighbors.

%I A226438 #8 Jul 17 2024 19:02:49
%S A226438 1,1,2,6,24,120,720,5038,40066,353556,3399246,35142546,387129588,
%T A226438 4515261680,55502974820,716557285110,9689420220510,136922907564972,
%U A226438 2018121531850482,30972340185946810,494190208052390752,8186609585709287112,140620153367124829272
%N A226438 Number of permutations of {1..n} with fewer than 5 interior elements having values lying between the values of their neighbors.
%H A226438 Alois P. Heinz, <a href="/A226438/b226438.txt">Table of n, a(n) for n = 0..481</a> (terms n = 1..210 from R. H. Hardin)
%e A226438 Some solutions for n=7
%e A226438 ..3....1....7....3....6....5....6....4....6....4....1....1....4....3....2....5
%e A226438 ..4....5....6....2....3....4....5....5....2....1....6....2....7....6....4....6
%e A226438 ..7....3....5....4....5....7....2....2....1....7....3....7....2....1....6....1
%e A226438 ..2....2....2....6....1....6....3....6....4....5....5....5....1....7....5....7
%e A226438 ..5....4....4....1....2....3....7....3....3....2....4....4....6....5....3....2
%e A226438 ..6....7....3....5....7....1....1....7....5....6....7....3....3....2....7....3
%e A226438 ..1....6....1....7....4....2....4....1....7....3....2....6....5....4....1....4
%Y A226438 Column 5 of A226441.
%K A226438 nonn
%O A226438 0,3
%A A226438 _R. H. Hardin_, Jun 06 2013
%E A226438 a(0)=1 prepended by _Alois P. Heinz_, Jul 17 2024