# 1973

This number is a prime. N.J.A. Sloane's A Handbook of Integer Sequences was first published by Academic Press in 1973. The smallest prime formed by using all possible end digits of multidigit primes, i.e., 1, 3, 7, and 9. [Gupta] 1973 is the year Picasso died. [Stroup] The least prime p that becomes composite if we add or subtract any power of 2 less than p/2. (The next few are 3181, 3967, 4889, 8363, 8923, ...) [TT2011]. [Caldwell] The smallest diagonal prime with distinct digits. (A diagonal prime is a prime of n^2 digits (n > 1) arranged left-right, top-down in a n-by-n matrix, where the diagonals are prime in each direction). [Loungrides] If we examine the possible end digits of the first million primes, then "1" occurs the least, followed by "9", then "7", with "3" occurring the most. [Honaker] The term "factoid" was coined in 1973 by American writer Norman Mailer. Mr. Prime Beef has been serving Alaskan communities since 1973. A 1973 stamp encouraged people to use the ZIP Code on letters and parcels. American physicist and computer pioneer Howard Aiken died on Pi Day in 1973. [Rolen] By luck, in 1973, a Bedouin — or nomadic Arab — guide named Eide Mariff came across a group of what looked like large, stone megaliths while crossing the Sahara. The discovery of Nabta Playa!