Backhouse's constant is a mathematical constant founded by N. Backhouse and is approximately 1.456 074 948.
It is defined by using the power series such that the coefficients of successive terms are the prime numbers:
(sequence A072508 in OEIS).
The limit was conjectured to exist by Backhouse which was later proved by P. Flajolet.
* Weisstein, Eric W., "Backhouse's Constant" from MathWorld.