[R] Declaring a density function with for loop

[chamilka]

I have an extended binomial distribution which has the following form: 

http://r.789695.n4.nabble.com/file/n4635699/kb.png 

Here alpha and beta are two parameters and x=0,1,2,3,...n (alike the
binomial distribution) 
I am writing a function to find out the densities (probabilities) of this
distribution for given values of alpha and beta. The below is the my
function... 

*dnewdis<-function(x,a,b,n) { 
      term<-0 
      for (j in 0:exp(10)) { 
           term=term+(((-1)**i)*(choose(b-1,i))*(beta(x+a+a*i,n-x+1))) 
           } 
      s=a*b*choose(n,x)*term 
      return(s) 
      }*

Since the sum inside the pdf runs from 0 to infinity, i restrict it to
exp(10)[a large number).... 
My questions are: 
1. Does the above function correct for the given pdf? 

In a journal paper, this distribution is evaluated for x=0,1,2...7 and n=7
and alpha=0.7 and beta=0.59 
so I used my function and got densities as: 
/> dnewdis(0,0.7,0.59,7) 
[1] 0.9527325 
> dnewdis(1,0.7,0.59,7) 
[1] 4.001476 
> dnewdis(2,0.7,0.59,7) 
[1] 10.40384 
> dnewdis(3,0.7,0.59,7) 
[1] 21.50127 
> dnewdis(4,0.7,0.59,7) 
[1] 38.70228 
> dnewdis(5,0.7,0.59,7) 
[1] 63.47174 
> dnewdis(6,0.7,0.59,7) 
[1] 97.32334 
> dnewdis(7,0.7,0.59,7) 
[1] 141.814/

which are very contradiction to the values provided in the paper!!! 
0.136090 
0.104612 
0.097393 
0.096992 
0.101203 
0.111303 
0.134110 
0.218296 

Also I am getting probabilities greater than 1 too?? 

Can you please tell me where am I doing wrong and I the function should be
corrected? 

I am a new R user!! 

Thank you very much for your kind help!

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