print "Wieferich primes less than 5000: "
for i = 1 to 5000
  if isWeiferich(i) then print i
next i
end

function isPrime(n)
if n < 2       then isPrime = 0 : goto [exit]
if n = 2       then isPrime = 1 : goto [exit]
if n mod 2 = 0 then isPrime = 0 : goto [exit]
isPrime = 1
for i = 3 to int(n^.5) step 2
  if n mod i = 0 then isPrime = 0 : goto [exit]
next i
[exit]
end function

function isWeiferich(p)
  if isPrime(p) = 0 then isWeiferich = 0 : goto [exit]
  q = 1
  p2 = p^2
  while p > 1
    q = (2*q) mod p2
    p = p - 1
  wend
  if q = 1 then
    isWeiferich = 1 : goto [exit]
  else
    isWeiferich = 0 : goto [exit]
  end if
[exit]
end function