OFFSET
1,1
COMMENTS
Sorted and duplicates removed, this gives A023195.
LINKS
Harry J. Smith and Chai Wah Wu, Table of n, a(n) for n = 1..10000 (terms 1..100 from Harry J. Smith)
FORMULA
EXAMPLE
sigma(2) = 3, sigma(4) = 7, sigma(9) = 13 are the first three prime terms of A000203. Hence the sequence starts 3, 7, 13.
MATHEMATICA
Select[DivisorSigma[1, Range[1000000]], PrimeQ] (* Harvey P. Dale, Nov 09 2012 *)
PROG
(Magma) [ c: n in [1..1000000] | IsPrime(c) where c:=SumOfDivisors(n) ]; // Klaus Brockhaus, Oct 21 2009
(PARI) je=[]; for(n=1, 1000000, if(isprime(sigma(n)), je=concat(je, sigma(n)))); je
(PARI) { n=0; for (m=1, 10^9, if(isprime(a=sigma(m)), write("b062700.txt", n++, " ", a); if (n==100, break)) ) } \\ Harry J. Smith, Aug 09 2009
(Python)
from sympy import isprime, divisor_sigma
A062700_list = [3]+[n for n in (divisor_sigma(d**2) for d in range(1, 10**4)) if isprime(n)] # Chai Wah Wu, Jul 23 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
Jason Earls, Jul 11 2001
EXTENSIONS
Edited by Klaus Brockhaus, Oct 21 2009
STATUS
approved