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A061299
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Least number whose number of divisors is A007304(n) (the n-th number that is the product of 3 distinct primes).
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8
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720, 2880, 46080, 25920, 184320, 2949120, 129600, 414720, 11796480, 1658880, 188743680, 3732480, 2073600, 26542080, 12079595520, 14929920, 48318382080, 106168320, 8294400, 3092376453120, 1698693120, 18662400, 238878720
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OFFSET
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1,1
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COMMENTS
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All terms are divisible by a(1)=720, the first entry.
All terms[=a(j)], not only arguments[=j] have 3 distinct prime factors at exponents determined by the p,q,r factors of their arguments: a(pqr)=RPQ.
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LINKS
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FORMULA
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a(n) = A005179(A007304(n)); Min{x; A000005(x)=pqr} p, q, r are distinct primes. If k = pqr and p > q > r then A005179(k) = 2^(p-1)*3^(q-1)*5^(r-1).
a(p*m*q) = 2^(q-1) * 3^(m-1) * 5^(p-1) for primes p < m < q;
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EXAMPLE
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n=5: A007304(5) = 78 = 2*3*13, A005179(78) = 184320 = (2^12)*(3^2)*(5^1) = a(5).
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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