OFFSET
1,1
COMMENTS
Subsequence of A247837.
EXAMPLE
Prime 13 is in sequence because there is prime 5 such that sigma(2*5-1) = sigma(9) = 13.
PROG
(Magma) Sort([a: p in PrimesUpTo(5000000) | IsPrime(a) where a is SumOfDivisors(2*p-1)]) # corrected by Jaroslav Krizek, Nov 16 2014
(PARI) forprime(p=1, 10^9, if(isprime(sigma(2*p-1)), print1(sigma(2*p-1), ", "))) \\ Derek Orr, Sep 25 2014
CROSSREFS
KEYWORD
nonn
AUTHOR
Jaroslav Krizek, Sep 24 2014
STATUS
approved