17th October

On this day in 1952, D H Lehmer announced that

2^{n}-1

for n = 2203 and 2281 are Mersenne primes. He was aided by a SWAC computer, with the first result taking 59 minutes. SWAC had been built in 1950 in Los Angeles.

The postage stamp of one of today's mathematicians at THIS LINK was issued in 1974.