Re: a curious answer
- To: mathgroup at smc.vnet.net
- Subject: [mg69201] Re: a curious answer
- From: "rick" <awass at umich.edu>
- Date: Fri, 1 Sep 2006 18:40:58 -0400 (EDT)
- References: <ed0rfa$skq$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Thank you for your response. One expects the occasional peculiar behavior from a CAS ( and people too but that is another matter ;-) rick wrote: > Hi, > > Can anyone explain these answers (Out[5] and Out[6])? > > Line 1 defines a polynomial in x that depends on n; > line 2 tests the definition when n= 4; > line 3 lists the coefficients of that polynomial and > line 4 checks the list when n= 4; lines 5 and 6 ask for a closed form > for the polynomial and coefficients (which is probably not possible). I > expected no answer-not gibberish. > > In[1]:= > k[n_]:=Expand[Product[(j*x+n-j),{j,1,n-1}]] > > In[2]:= > k[4] > > Out[2]= > \!\(6 + 26\ x + 26\ x\^2 + 6\ x\^3\) > > In[3]:= > cL[s_]:=CoefficientList[k[s],x] > > > In[4]:= > cL[4] > > Out[4]= > {6,26,26,6} > > In[5]:= > cL[n] > > Out[5]= > \!\({\(-\((\(-1\))\)\^n\)\ n\^\(\(-1\) + n\)\ \(\((\(-1\) + n)\)!\)}\) > > In[6]:= > k[n] > > Out[6]= > \!\(\(-\((\(-1\))\)\^n\)\ n\^\(\(-1\) + n\)\ \(\((\(-1\) + n)\)!\)\) > > > Thanks,