%I A005212
%S A005212 0,1,0,6,0,120,0,5040,0,362880,0,39916800,0,6227020800,0,
%T A005212 1307674368000,0,355687428096000,0,121645100408832000,0,
%U A005212 51090942171709440000,0,25852016738884976640000,0
%N A005212 n! if n is odd otherwise 0 (from the Taylor series for sin x).
%C A005212 Normally sequences like this are not included, since with the alternating 
               0's deleted it is already in the database.
%C A005212 Stirling transform of a(n)=[1,0,6,0,120,0,5040,...] is A089677(n)=[1,
               1,7,37,271,...]. - Michael Somos Mar 04 2004
%C A005212 Stirling transform of a(n-1)=[0,1,0,6,0,120,0,...] is A00670(n-1)=[0,
               1,3,13,75,...]. - Michael Somos Mar 04 2004
%C A005212 Stirling transform of a(n-1)=[1,1,0,6,0,120,0,...] is A052856(n-1)=[1,
               2,4,14,76,...]. - Michael Somos Mar 04 2004
%D A005212 Hofstadter, D. R., Fluid Concepts and Creative Analogies: Computer Models 
               of the Fundamental Mechanisms of Thought, (together with the Fluid 
               Analogies Research Group), NY: Basic Books, 1995.
%H A005212 <a href="Sindx_Fa.html#factorial">Index entries for sequences related 
               to factorial numbers</a>
%p A005212 BB:=[T,{T=Prod(Z,F),F=Sequence(B),B=Prod(Z,Z)}, labeled]: seq(count(BB,
               size=i),i=0..24); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), 
               Apr 22 2007
%p A005212 a:=n->n!-sum((-1)^k*n!, k=0..n): seq(a(n), n=0..24); - Zerinvary Lajos 
               (zerinvarylajos(AT)yahoo.com), Mar 25 2008
%p A005212 a:=n->n!-(-1)^n*n!: seq(a(n)/2, n=0..24); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), 
               Mar 25 2008
%o A005212 (PARI) a(n)=if(n<0,0,if(n%2,n!,0))
%Y A005212 Sequence in context: A145223 A072129 A085511 this_sequence A167028 A052679 
               A134680
%Y A005212 Adjacent sequences: A005209 A005210 A005211 this_sequence A005213 A005214 
               A005215
%K A005212 nonn
%O A005212 0,4
%A A005212 Russ Cox (rsc(AT)swtch.com)