possible error in A005835

[Joerg Arndt]

Also it seems that 6 should _not_ be in the sequence:

pari/gp
N=72  \\ up to this value
vv=vector(N);
{ for(n=2, N,
     if ( isprime(n), next() );
     d=divisors(n);
     d=vector(#d-2,j,d[j+1]);  \\ not n, not 1
\\     print(n, ":: ", d);

     for (k=1, (1<<#d)-1,  \\ all subsets
        t=vecextract(d, k);
        if ( n==sum(j=1,#t,t[j]),
            vv[n] += 1;
\\            print(n, ": ", t);  \\ print subset that works
\\            break();  \\ speedup, just find one sum
        );
     );
  ); }

for (j=1, #vv, if (vv[j]>0, print1(j,", ")))  \\ A005835 (after correction)

\\ this prints:
12, 18, 24, 30, 36, 40, 42, 48, 54, 56, 60, 66, 72, 



* Maximilian Hasler <maximilian.hasler at gmail.com> [Apr 06. 2008 13:16]:
> I agree, I sent the following message to Neil and to the author 7 days
> ago, so far without reply.
> Maximilian
> ---------- Forwarded message ----------
> From: Maximilian Hasler <Maximilian.Hasler at martinique.univ-ag.fr>
> Date: Sun, Mar 30, 2008 at 3:09 AM
> Subject: bug in A005835 ?
> To: "N. J. A. Sloane" <njas at research.att.com>,
> reinhard.zumkeller at gmail.com, reinhard.zumkeller at lhsystems.com
> 
> I may misunderstand something, but IMO the %C is wrong, I'd rather be
>  tempted to say:
> 
>  %C A005835 Weird numbers (A006037) are neither in this sequence,
>  neither in A005100.
>  - Maximilian F. Hasler (www.univ-ag.fr/~mhasler), Mar 30 2008
> 
> 
>  %I A005835 M4094
>  %S A005835 6,12,18,20,24,28,30,36,40,42,48,54,56,60,66,72,78,80,84,88,90,96,100,102,
>  %N A005835 Pseudoperfect (or semiperfect) numbers: some set of proper
>  divisors of n sums to n.
>  %C A005835 A033630(a(n)) > 1; complement of A005100. - Reinhard
>  Zumkeller (reinhard.zumkeller(AT)gmail.com),
>                Mar 02 2007
>  (snip)