Prime numbers and primality testing is a Restricted Group with 1137 members. Yahoo Groups curio on powers of e (1st appearing leading right-truncatables of each length concatenated) James Merickel Message 1 of 1 , Jan 7, 2014 This is the concatenation of the first right-truncatable primes of lengths 1 to 8 (maximum) to arise as the leading digits of a positive integral power of the base of natural logarithms (The sense of 'first' should be clear, and 'right-truncatable' means that removing digits sequentially from the right down to one digit leaves a prime at each step (and also applying a convention of including 1-digit primes as right truncatable)): 273373373323333719333233993323399339. I suppose for a question I would ask how one would address how 'coincidental' the result is. The feature identified first and foremost as coincidental is to be found in the factorization of this number and the numbers prior to appending the last and last 2 (8- & 7-digit) numbers (The whole thing is semiprime with factor 100003, the one excluding the 8-digit number has largest prime factor terminating with 7777, and the one also excluding the 7-digit has largest prime factor terminating with 000077). JGM