OFFSET
1,1
COMMENTS
The corresponding number of prime factors is 1, 1, 1, 3, 2, 2, 2, 2, 4, 4, 5, 4, 2, ...
EXAMPLE
3 is in the sequence since 3 and 5 are twin primes pair, and 2^3-1=7 and 2^5-1=31 are both primes, thus having the same number of prime factors.
71 is in the sequence since 71 and 73 are twin primes pair and 2^71-1 and 2^73-1 both have 3 prime factors.
MATHEMATICA
Do[If[PrimeQ[n]&&PrimeQ[n+2]&&PrimeOmega[2^n-1]==PrimeOmega[2^(n+2)-1], Print[n]], {n, 1, 200}]
PROG
(PARI) isok(p) = isprime(p) && isprime(p+2) && (omega(2^p-1) == omega(2^(p+2)-1)); \\ Michel Marcus, Oct 02 2018
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Amiram Eldar, Oct 01 2018
STATUS
approved