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A077327
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Smallest number beginning with 2 and having exactly n distinct prime divisors.
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9
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2, 20, 204, 210, 2310, 200970, 2012010, 20030010, 223092870, 20090100030, 200560490130, 20055767721990, 2000029432190790, 20384767656323070, 2000848249650860610, 200001648981983238390, 2183473617971732996910
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OFFSET
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1,1
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LINKS
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EXAMPLE
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a(1) = 2, a(5) = 2310 = 2*3*5*7*11.
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PROG
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(Python)
from sympy import primorial, factorint
m, start_digit = primorial(n), str(begins_with)
while len(factorint(m)) != n or str(m)[0] != start_digit:
m += 1
s = str(m)
if s[0] == start_digit: continue
elif s[0] < start_digit: m = int(start_digit+'0'*(len(s)-1))
else: m = int(start_digit+'0'*len(s))
return m
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CROSSREFS
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KEYWORD
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base,nonn
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AUTHOR
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EXTENSIONS
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Correct a(2) and a(3), add a(6)-a(11) from Ray Chandler, Apr 17 2005
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STATUS
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approved
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