%I A001266 M4426 N1871
%S A001266 0,0,1,7,45,323,2621,23811,239653,2648395,31889517,415641779,5830753109,
%T A001266 87601592187,1403439027805,23883728565283,430284458893701,8181419271349931,
%U A001266 163730286973255373,3440164703027845395,75718273707281368117,1742211593431076483419
%N A001266 One-half the number of permutations of length n without rising or falling 
               successions.
%C A001266 (1/2) times number of permutations of 12...n such that none of the following 
               occur: 12, 23, ..., (n-1)n, 21, 32, ..., n(n-1).
%D A001266 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A001266 N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 
               (includes this sequence).
%D A001266 F. N. David, M. G. Kendall and D. E. Barton, Symmetric Function and Allied 
               Tables, Cambridge, 1966, p. 263.
%D A001266 J. Riordan, A recurrence for permutations without rising or falling successions. 
               Ann. Math. Statist. 36 (1965), 708-710.
%F A001266 (1/2) times coefficient of t^0 in S[n](t) defined in A002464.
%Y A001266 Sequence A002464 divided by 2 for n >= 2. A diagonal of A010028.
%Y A001266 Sequence in context: A103719 A134437 A018927 this_sequence A071971 A006680 
               A034471
%Y A001266 Adjacent sequences: A001263 A001264 A001265 this_sequence A001267 A001268 
               A001269
%K A001266 nonn
%O A001266 2,4
%A A001266 N. J. A. Sloane (njas(AT)research.att.com).
%E A001266 More terms from Barbara Haas Margolius (margolius(AT)math.csuohio.edu) 
               2/16/01