from sympy import primerange
from heapq import heappush, heappop

top = 10**9
heap = [(3, 3), (4, 2)]
last = 2
primes = primerange(5, top)
seen = {}

while heap:
    n, p = heappop(heap)
    gap = n - last
    if not (gap in seen):
        seen[gap] = last
    last = n
    m = n * p
    if m < top:
        heappush(heap, (m, p))
    if n == p:
        try:
            m = primes.next()
            if m < top:
                heappush(heap, (m, m))
        except:
            pass

for x, y in sorted(seen.items()):
    print "a(%d) = %d" % (x, y)