A321114 - OEIS

%I #5 Oct 27 2018 16:21:09

%S 74,528,3550,23284,151096,974472,6252218,39892080,253727936,

%T 1611713082,10230277342,64911693746,411813289010,2612751224650,

%U 16579665387410,105238154698686,668214471729004,4244427360639456,26970709343926262,171451330997483406,1090351846894142818

%N Number of permutations p of [n] such that in 0p the largest up-jump equals seven and no down-jump is larger than 2.

%H Alois P. Heinz, <a href="/A321114/b321114.txt">Table of n, a(n) for n = 7..1000</a>

%p b:= proc(u, o, k) option remember; `if`(u+o=0, 1,

%p       add(b(u-j, o+j-1, k), j=1..min(2, u))+

%p       add(b(u+j-1, o-j, k), j=1..min(k, o)))

%p     end:

%p a:= n-> (k-> b(0, n, k)-b(0, n, k-1))(7):

%p seq(a(n), n=7..30);

%Y Column k=7 of A291680.

%K nonn

%O 7,1

%A _Alois P. Heinz_, Oct 27 2018