%I A123022
%S A123022 1,1,2,1,0,1,0,3,0,15,0,105,0,945,0,10395,0,135135,0,2027025,0,34459425,
               0,
%T A123022 654729075,0,13749310575,0,316234143225,0,7905853580625,0,213458046676875,
               0,
%U A123022 6190283353629375,0,191898783962510625,0,6332659870762850625,0
%V A123022 1,1,-2,-1,0,-1,0,-3,0,-15,0,-105,0,-945,0,-10395,0,-135135,0,-2027025,
               0,-34459425,0,
%W A123022 -654729075,0,-13749310575,0,-316234143225,0,-7905853580625,0,-213458046676875,
               0,
%X A123022 -6190283353629375,0,-191898783962510625,0,-6332659870762850625,0
%N A123022 a(n)=n!*b(n) where b(0)=b(1)=1, b(n)=(n-4)b(n-2)/[n(n-1)] for n>=2.
%D A123022 Richard Bronson, Schaum's Outline of Modern Introductory Differential 
               Equations, MacGraw-Hill, New York,1973, page 99, solved problem 19.1.
%p A123022 b[0]:=1: b[1]:=1: for n from 2 to 40 do b[n]:=(n-4)*b[n-2]/n/(n-1) od: 
               seq(n!*b[n],n=0..40);
%t A123022 a[n_] := a[n] = (n - 4)*a[n - 2]/(n*(n - 1)); a[0] = 1; a[1] = 1; Table[a[n]*n!, 
               {n, 0, 30}]
%Y A123022 Sequence in context: A158461 A144152 A116675 this_sequence A072943 A072175 
               A092147
%Y A123022 Adjacent sequences: A123019 A123020 A123021 this_sequence A123023 A123024 
               A123025
%K A123022 sign
%O A123022 0,3
%A A123022 Roger Bagula (rlbagulatftn(AT)yahoo.com), Sep 24 2006
%E A123022 Edited by N. J. A. Sloane (njas(AT)research.att.com), Oct 01 2006 and 
               Nov 24 2006