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%I
%S 0,0,0,0,0,2,22,226,2198,22120,236968,2732268,33940644,453148422,
%T 6480322210,98907371822,1605581578202,27631315113916,502618772515748,
%U 9637245372790760,194291040277517688,4109014039030693578,90968013940830446574,2104072961763468757082
%N Number of permutations of length n with exactly 4 rising or falling successions.
%C Permutations of 12...n such that exactly 4 of the following occur: 12, 23, ..., (n-1)n, 21, 32, ..., n(n-1).
%D F. N. David, M. G. Kendall and D. E. Barton, Symmetric Function and Allied Tables, Cambridge, 1966, p. 263.
%D J. Riordan, A recurrence for permutations without rising or falling successions. Ann. Math. Statist. 36 (1965), 708-710.
%H Alois P. Heinz, <a href="/A086855/b086855.txt">Table of n, a(n) for n = 0..200</a>
%F Coefficient of t^4 in S[n](t) defined in A002464.
%p S:= proc(n) option remember; `if`(n<4, [1, 1, 2*t, 4*t+2*t^2]
%p [n+1], expand((n+1-t)*S(n-1) -(1-t)*(n-2+3*t)*S(n-2)
%p -(1-t)^2*(n-5+t)*S(n-3) +(1-t)^3*(n-3)*S(n-4)))
%p end:
%p a:= n-> ceil(coeff(S(n), t, 4)):
%p seq (a(n), n=0..25); # _Alois P. Heinz_, Jan 11 2013
%Y Cf. A002464, A000130, A000349, A001267, A086852, A086853. A diagonal of A001100.
%Y Twice A001268.
%K nonn
%O 0,6
%A _N. J. A. Sloane_, Aug 19 2003
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