Re^2: Error-finding program

[Richard Mathar]

> From seqfan-owner at ext.jussieu.fr  Wed Oct 25 21:07:37 2006
> Return-Path: <seqfan-owner at ext.jussieu.fr>
> To: seqfan at ext.jussieu.fr
> Subject: Re: Error-finding program
> ..
> A026302 Should certainly be monotonic; I don't know what the correct
> value of a(18) is.

The fourth digit of a(18) was missing:
	
0 1
1 2
2 9
3 44
4 230
5 1242
6 6853
7 38376
8 217242
9 1239980
10 7123765
11 41141916
12 238637282
13 1389206210
14 8112107475
15 47495492400
16 278722764954
17 1638970147188
18 9654874654438
19 56965811111240
20 336590781348276
21 1991357644501170

in PARI:

A026300(n,k)={
	if(n<0 || k < 0,
		return(0) ;
	) ;
	if(n<=1,
		1,
		if(k==0,
			1,
			sum(i=0,k/2,
				binomial(n,2*i+n-k)*(binomial(2*i+n-k,i)-binomial(2*i+n-k,i-1))
			) ;
		) ;
	) ;
}

A026302(n)={
	A026300(2*n,n) ;
}

{
	for(n=0,21,
		print(n," ",A026302(n))
	) ;
}