1.1970449

This number is neither prime nor composite.

Analogous to Brun's constant for twin primes, this constant is the sum of the reciprocals of all pairs of Cousin primes (excluding the initial 1/3 + 1/7), i.e., (1/7 + 1/11) + (1/13 + 1/17) + (1/19 + 1/23) + (1/37 + 1/41) + (1/43 + 1/47) + (1/67 + 1/71) + ... Theoretical Physicist Marek Wolf made this approximation through 2^42, as described in the paper "Generalized Brun's constants." [Post]