arraybase 1
max = 2000
global stern
dim stern(max+2)

subroutine SternBrocot()
	stern[1] = 1
	stern[2] = 1

	i = 2 : n = 2 : ub = stern[?]

	while i < ub
		i += 1
		stern[i] = stern[n] + stern[n-1]
		i += 1
		stern[i] = stern[n]
		n += 1
	end while
end subroutine

function gcd(x, y)
	while y
		t = y
		y = x mod y
		x = t
	end while
	gcd = x
end function

call SternBrocot()

print "The first 15 are: ";
for i = 1 to 15
	print stern[i]; " ";
next i

print : print
print "Index    First nr."
d = 1
for i = 1 to max
	if stern[i] = d then
		print i; chr(9); stern[i]
		d += 1
		if d = 11 then d = 100
		if d = 101 then exit for
		i = 0
	end if
next i

print : print
d = 0
for i = 1 to 1000
	if gcd(stern[i], stern[i+1]) <> 1 then
		d = gcd(stern[i], stern[i+1])
		exit for
	end if
next i

if d = 0 then
	print "GCD of two consecutive members of the series up to the 1000th member is 1"
else
	print "The GCD for index "; i; " and "; i+1; " = "; d
end if