PARI's commands

[kar_bon]

Originally Posted by science_man_88

so in other terms:

forprime(p=1,1500,if(isprime(p*10^2+1),print(p*10^2+1)))

NO!

"print(p)" and that will give the correct answers!

[3.14159]

Title is corrected.

[science_man_88]

his sequence he gave is A180469 (already up by him) and it's not the p values it's the full values he listed.

[kar_bon]

The title says "Primes such that p * 100 + 1 is also prime."

But to which value is p*100+1 also prime?

The word "Primes" and "p*100+1 also prime" refer to different values!

"also prime" to the value p obviously meant, so p has to be listed here, not p*100+1!

PS:
And the given PARI code is also false

p10n(a, x) = { for(n=a, x, if(isprime(n)&isprime(n*10^2+1), print(10^2+1)) )};

This will ouput only 101 evertime a value is found!

Correct like this:
"Primes p such that p*100+1 also prime"
"Values: 7, 13, 19, 37, 61, 67, ..."

[science_man_88]

Originally Posted by kar_bon

PS:
And the given PARI code is also false

p10n(a, x) = { for(n=a, x, if(isprime(n)&isprime(n*10^2+1), print(10^2+1)) )};

This will ouput only 101 evertime a value is found!

yeah I know I've been experimenting with it lol

[science_man_88]

Originally Posted by kar_bon

Correct like this:
"Primes p such that p*100+1 also prime"
"Values: 7, 13, 19, 37, 61, 67, ..."

also I could see using another if to branch if(p<default(primelimit),code1,code2) type idea.

[CRGreathouse]

Originally Posted by science_man_88

also I could see using another if to branch if(p<default(primelimit),code1,code2) type idea.

How about this, for your usual preoccupation with looping over primes that 'may' be huge:

forallprime(start,stop,ff)={
  my(d=default(primelimit));
  if (type(ff) != "T_CLOSURE", error("ff must be a function! For example, forallprime(10,100,n->print(n))"));
  forprime(p=start,min(stop,d), ff(p));
  if(stop > d,
    print("\nWarning, "stop" > primelimit, calculation may be slow");
    for(n=precprime(d)+1, stop,
      if(isprime(n), ff(n))
    )
  )
};
addhelp(forallprime, "forallprime(start, stop, ff): Executes the closure (function) ff for all the primes between start and stop.");

[science_man_88]

I'm useless as this code appears to do nothing useful no matter what I do if i try to print the result it give me an error oddly if i use next() as well it doesn't give me that error but it only prints once and only exactly what I type even if it's a variable you use, plus the added bonus of not throwing a out of limits error if i go over primelimit.

[CRGreathouse]

Sorry, typo... replace T_CLOSURE with t_CLOSURE. (That'll teach me to post without checking my programs!)

[science_man_88]

Originally Posted by CRGreathouse

Sorry, typo... replace T_CLOSURE with t_CLOSURE. (That'll teach me to post without checking my programs!)

yeah I got it working under that lol. wonder how many primes I could fit on my drives lol using my ipod and a few other removables + main drive I get

211,474,722,816
249,515,175,936
008,002,691,072
006,624,665,600
475,617,255,424 bytes if i did the math right

apparently doing math visually on here isn't a good way although I got nearly accurate I get 372 as the ending by calculator.

[CRGreathouse]

Depends on what size primes you store and how you store them, naturally.