394 years ago…
John Smith leaves Virginia to return to England.
          395
  395 is the sum of 3 consecutive prime numbers:
  127 + 131 + 137
  395 is also the sum of 5 consecutive primes:
  71 + 73 + 79 + 83 + 89
          396
  396 has prime factors in a “neat” numerical arrangement:
  396 = 112233
  the first 3 digits are used twice and in order.
396 - Big block Chevy! grunt grunt grunt
SamTrans Route 397 (San Francisco to Palo Alto, California, by train)
          397
  397 is the sum of 2 squares 19[sup]2[/sup] + 6[sup]2[/sup]
  = 361 + 36
Hmmm seems we’re getting double postings.
Luckily, it has remained in numerical order.
Any rules for taking turns OR should we just let these fall where they may?
I’d say let them fall where they may. Can’t really stop simulposts…
          398
The number 398 can be derived using 3 consecutive cubes:
              9[sup]3[/sup] = 729
          10[sup]3[/sup] = 1,000
Minus 11[sup]3[/sup] = -1,331
Equals             398
  399
The sum of eleven consecutive primes: 17 19 23 29 31 37 41 43 47 53 and 59
  400
  400 is a perfect square = 20[sup]2[/sup]
Plan your retirement with a 401K.
From the European Agency for Safety and Health at Work, you can get:
Issue 402 - The State of Occupational Safety and Health in the European Union – Pilot Study; Summary Report
Rather interesting, I think. YMMV.
          403
  403 has 2 double digit prime factors and these factors are pallindromes
  403 = 13 * 31
  404
The dreaded Error 404 that shows up much too frequently when surfing the 'Net by clicking on links that are ancient.
405
It’s a movie, apparently
          405
  3[sup]4[/sup]*5 = 405
  Nice 3 4 5 numerical progression
          406
The 28th triangular number, being the sum of the integers 1 through 28.
Perhaps a better description of the 403 posting would be its prime factors are mirror images of each other.
407 bc Lysander defeats Athenian fleet off Notium.
          407
  407 is the sum of 3 consecutive primes: 131, 137 & 139