What's the exponent required for 10, 100 or 1000 megadigit Mersenne numbers? The nearest prime exponents and the numbers of digits of their corresponding Mersenne numbers?

How were those calculated? See the attachment for a handy list. It's been checked against

http://oeis.org/A034887 which gave the formula floor(n*log(2)/log(10)) + 1

Also included is a rough ballpark estimate of what's feasible on a GTX1070 in CUDALucas 2.06.

Top of reference tree:

https://www.mersenneforum.org/showpo...22&postcount=1