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A182683
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a(n) = the smallest n-digit number with exactly 12 divisors, a(n) = 0 if no such number exists.
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1
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0, 60, 108, 1012, 10004, 100004, 1000012, 10000025, 100000012, 1000000025, 10000000012, 100000000004, 1000000000017, 10000000000004, 100000000000012, 1000000000000004, 10000000000000025, 100000000000000004, 1000000000000000017, 10000000000000000034, 100000000000000000012, 1000000000000000000025, 10000000000000000000004, 100000000000000000000004
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OFFSET
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1,2
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COMMENTS
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a(n) = the smallest n-digit number of the form p^11, p^5*q, p^3*q^2 or p^2*q*r (p, q, r distinct primes), a(n) = 0 if no such number exists.
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LINKS
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Table of n, a(n) for n=1..24.
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FORMULA
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A000005(a(n)) = 12.
a(n) <= A182684(n).
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MATHEMATICA
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Table[k=10^(n-1); While[k<10^n && DivisorSigma[0, k] != 12, k++]; If[k==10^n, k=0]; k, {n, 20}]
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CROSSREFS
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Cf. A030630, A182684.
Sequence in context: A044001 A008887 A217738 * A174601 A096490 A056866
Adjacent sequences: A182680 A182681 A182682 * A182684 A182685 A182686
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KEYWORD
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nonn,base
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AUTHOR
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Jaroslav Krizek, Nov 27 2010
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STATUS
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approved
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