Prime's notation in RFC3526 about Diffie Hellman Key Exchange

Question

In RFC3526, the prime is presented by 2^1536 - 2^1472 - 1 + 2^64 * { [2^1406 pi] + 741804 } form

I wanna know the "[2^1406 pi]" part means what

THKS

Answer 1

The [] notation represents the greatest integer or floor function. Therefore [2^1406 pi] means multiply pi (3.141...) by 2^1406 and throw away the fractional part. Enter Floor[2^1406 * Pi] into Wolfram Alpha to see the result.