OFFSET
1,1
COMMENTS
LINKS
Donovan Johnson and Chai Wah Wu, Table of n, a(n) for n = 1..10385 [Terms from 1 to 500 from Donovan Johnson]
EXAMPLE
4 is in the sequence because both sigma(4)=7 and sigma(4^2)=31 are primes.
PROG
(PARI) isok(n) = isprime(sigma(n)) && isprime(sigma(n^2)); \\ Michel Marcus, Nov 26 2013
(Python)
from sympy import isprime, divisor_sigma
A232444_list = [2]+[n for n in (d**2 for d in range(1, 10**4)) if isprime(divisor_sigma(n)) and isprime(divisor_sigma(n**2))] # Chai Wah Wu, Jul 23 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
Alex Ratushnyak, Nov 24 2013
EXTENSIONS
a(6)-a(12) from Michel Marcus, Nov 26 2013
a(13)-a(29) from Alex Ratushnyak, Nov 26 2013
STATUS
approved