OFFSET
1,1
COMMENTS
Could be called "Sophie Germain anti-primes" or "anti-Sophie Germain primes". Inspired by the Gerasimov link.
Sophie Germain primes are such that 2p+1 is also prime, where 2 is the number of divisors of p. Here this is replaced with the number of anti-divisors.
There are only 47 such primes below 10^7.
LINKS
Donovan Johnson, Table of n, a(n) for n = 1..1000
J. S. Gerasimov, Sophie Germain nonprimes [title corrected], SeqFan mailing list, Jan 15 2013
PROG
(PARI) {forprime(n=1, default(primelimit), isprime(A066272(n)*n+1) & print1(n", "))}
CROSSREFS
KEYWORD
nonn
AUTHOR
M. F. Hasler, Jan 15 2013
STATUS
approved