Max: 1000
a: array.of: Max 0

loop 0..Max-2 'n [
    if 0 =< n-1 [
        loop (n-1)..0 'm [
            if a\[m]=a\[n] [
                a\[n+1]: n-m
                break
            ]
        ]
    ]
]

print "The first ten terms of the Van Eck sequence are:"
print first.n:10 a

print ""
print "Terms 991 to 1000 of the sequence are:"
print last.n:10 a