%I A007683 M2289
%S A007683 1,3,3,9,21,33,1173,13515,113739,532209,6284379,264830061,5897799141,
%T A007683 104393462439,1459983940203,10308316834293,308010522508395,19576840707893409,
%U A007683 726806556195360069,22261372611370303875,591210850189999983099
%V A007683 1,-3,3,9,21,-33,-1173,-13515,-113739,-532209,6284379,264830061,5897799141,
%W A007683 104393462439,1459983940203,10308316834293,-308010522508395,-19576840707893409,
%X A007683 -726806556195360069,-22261372611370303875,-591210850189999983099
%N A007683 a(1) = 1; a(n) = - Sum (n+k)!a(k)/(2k)!, k = 1..n-1.
%D A007683 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A007683 H. W. Gould, A class of binomial sums and a series transformation, Utilitas 
               Math., 45 (1994), 71-83.
%Y A007683 Cf. A067000.
%Y A007683 Sequence in context: A038221 A099465 A099094 this_sequence A059728 A083008 
               A117976
%Y A007683 Adjacent sequences: A007680 A007681 A007682 this_sequence A007684 A007685 
               A007686
%K A007683 sign
%O A007683 1,2
%A A007683 N. J. A. Sloane (njas(AT)research.att.com).