Search: id:A000349
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%I A000349 M3932 N1617
%S A000349 0,0,0,1,5,24,128,835,6423,56410,554306,6016077,71426225,920484892,12793635300,
%T A000349 190730117959,3035659077083,51371100102990,920989078354838,17437084517068465,
%U A000349 347647092476801301,7280060180210901232,159755491837445900120,3665942433747225901707
%N A000349 One-half the number of permutations of length n with exactly 2 rising 
               or falling successions.
%C A000349 (1/2) times number of permutations of 12...n such that exactly 2 of the 
               following occur: 12, 23, ..., (n-1)n, 21, 32, ..., n(n-1).
%D A000349 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A000349 N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 
               (includes this sequence).
%D A000349 F. N. David, M. G. Kendall and D. E. Barton, Symmetric Function and Allied 
               Tables, Cambridge, 1966, p. 263.
%D A000349 J. Riordan, A recurrence for permutations without rising or falling successions. 
               Ann. Math. Statist. 36 (1965), 708-710.
%F A000349 Coefficient of t^2 in S[n](t) defined in A002464, divided by 2.
%Y A000349 Cf. A002464, A000130, A086852. Equals A086853/2. A diagonal of A010028.
%Y A000349 Sequence in context: A055825 A006326 A058120 this_sequence A036919 A020067 
               A066118
%Y A000349 Adjacent sequences: A000346 A000347 A000348 this_sequence A000350 A000351 
               A000352
%K A000349 nonn
%O A000349 0,5
%A A000349 N. J. A. Sloane (njas(AT)research.att.com).

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