PARI's commands

[CRGreathouse]

Originally Posted by science_man_88

return aliquot sequence n

Give me an example.

[science_man_88]

[8,7,1] ?

[kar_bon]

Originally Posted by CRGreathouse

Give me an example.

Aliquot Sequence:

(N) -> Sum of proper divisors of N (Sigma(N)).

Example sequence:
s₀= N
s₁ = _n-1 - s_n-1

So for N=10 you get:
10 = 10+ 5 + 2 + 1 = 18 -> 18-10 = 8
8 = 8 + 4 + 2 + 1 = 15 -> 15-8 = 7
7 = 7 + 1 = 8 -> 8-7 = 1 STOP

Ses also the thread here and the first open sequence (without ending found yet) here
and my summary pages (Menu Aliquot Seqs.) here (not yet fully updated).

[CRGreathouse]

kar_bon, I understand what an aliquot sequence is, but that doesn't tell me what sm88 wants.

I take it from his last post that he wants a vector with last term 1 and first term the input, where v[i+1] = sigma(v[i]) - v[i]. But of course it's not even proven that such a vector exists for all n...!

[science_man_88]

basically I wanted to try and find all of the aliquot sequences but I made code that no matter what and I may have an earlier code than this but no matter what I get an error for all but perfect numbers.

[science_man_88]

%68 = (n)->v=vector(1,x,n);for(a=2,10,d=sumdiv(v[a-1],X,X=X)-v[a=1];v=concat(v,d))
(13:51) gp > Aliquot(4)
  ***   user interrupt after 27,032 ms.
  ***   bug in PARI/GP (Segmentation Fault), please report

looks like something else gone wrong now.

[CRGreathouse]

It may be worth pointing out that the aliquot function is calculated in Pari as
sigma(n)-n
and so essentially all of your program will be doing 'the rest', whatever that is.

[science_man_88]

Originally Posted by CRGreathouse

It may be worth pointing out that the aliquot function is calculated in Pari as
sigma(n)-n
and so essentially all of your program will be doing 'the rest', whatever that is.

put the next one in the sequence etc.

[science_man_88]

got it working now but I get a error of:

*** sigma: couldn't find a suitable name for a tempdir (MPQS).

the codes are:

Alistep(n)=sigma(n)-n

And :

Aliquot(n)= v=vector(1,x,n);for(a=2,1000,d=Alistep(v[a-1]);v=concat(v,d);if(d==n || d==1,break()));print(v)

And I tried :

for(n=2,1000,Aliquot(n))

[science_man_88]

I'm an idiot the error I was getting was because 276 never ends i think lol or at least in my memory.

[CRGreathouse]

Originally Posted by science_man_88

I'm an idiot the error I was getting was because 276 never ends i think lol or at least in my memory.

You could have it print at every step to see what's going on. Also, you could durn up the debug setting and watch the details of the factorization:
default(debug,4)