OFFSET
1,1
COMMENTS
The next term, if it exists, must be greater than 10^8.
Each term is a square.
Most of the terms seem to be of the form p^2 for some prime p. Out of the first 10539 terms, 6 of them are not of the form p^2. - Chai Wah Wu, Jul 13 2016
LINKS
Chai Wah Wu, Table of n, a(n) for n = 1..10539
EXAMPLE
729 is in the sequence because sigma(729) = 1093 and 1091 are both primes.
PROG
(Magma) [n: n in[1..10^7] | IsPrime(SumOfDivisors(n)) and IsPrime(SumOfDivisors(n)-2)]
(Python)
from sympy import isprime, divisor_sigma
A274963_list = [n for n, s in ((d**2, divisor_sigma(d**2)) for d in range(1, 10**3)) if isprime(s) and isprime(s-2)] # Chai Wah Wu, Jul 13 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
Jaroslav Krizek, Jul 12 2016
STATUS
approved